tree-wide: fix assorted typos all over the place
[linux-2.6.git] / fs / ntfs / file.c
index be9fd1d..43179dd 100644 (file)
@@ -1,7 +1,7 @@
 /*
  * file.c - NTFS kernel file operations.  Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2005 Anton Altaparmakov
+ * Copyright (c) 2001-2007 Anton Altaparmakov
  *
  * This program/include file is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as published
  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
-#include <linux/pagemap.h>
 #include <linux/buffer_head.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+#include <linux/sched.h>
+#include <linux/swap.h>
+#include <linux/uio.h>
+#include <linux/writeback.h>
 
+#include <asm/page.h>
+#include <asm/uaccess.h>
+
+#include "attrib.h"
+#include "bitmap.h"
 #include "inode.h"
 #include "debug.h"
+#include "lcnalloc.h"
+#include "malloc.h"
+#include "mft.h"
 #include "ntfs.h"
 
 /**
@@ -48,7 +61,7 @@ static int ntfs_file_open(struct inode *vi, struct file *filp)
 {
        if (sizeof(unsigned long) < 8) {
                if (i_size_read(vi) > MAX_LFS_FILESIZE)
-                       return -EFBIG;
+                       return -EOVERFLOW;
        }
        return generic_file_open(vi, filp);
 }
@@ -56,6 +69,2083 @@ static int ntfs_file_open(struct inode *vi, struct file *filp)
 #ifdef NTFS_RW
 
 /**
+ * ntfs_attr_extend_initialized - extend the initialized size of an attribute
+ * @ni:                        ntfs inode of the attribute to extend
+ * @new_init_size:     requested new initialized size in bytes
+ * @cached_page:       store any allocated but unused page here
+ * @lru_pvec:          lru-buffering pagevec of the caller
+ *
+ * Extend the initialized size of an attribute described by the ntfs inode @ni
+ * to @new_init_size bytes.  This involves zeroing any non-sparse space between
+ * the old initialized size and @new_init_size both in the page cache and on
+ * disk (if relevant complete pages are already uptodate in the page cache then
+ * these are simply marked dirty).
+ *
+ * As a side-effect, the file size (vfs inode->i_size) may be incremented as,
+ * in the resident attribute case, it is tied to the initialized size and, in
+ * the non-resident attribute case, it may not fall below the initialized size.
+ *
+ * Note that if the attribute is resident, we do not need to touch the page
+ * cache at all.  This is because if the page cache page is not uptodate we
+ * bring it uptodate later, when doing the write to the mft record since we
+ * then already have the page mapped.  And if the page is uptodate, the
+ * non-initialized region will already have been zeroed when the page was
+ * brought uptodate and the region may in fact already have been overwritten
+ * with new data via mmap() based writes, so we cannot just zero it.  And since
+ * POSIX specifies that the behaviour of resizing a file whilst it is mmap()ped
+ * is unspecified, we choose not to do zeroing and thus we do not need to touch
+ * the page at all.  For a more detailed explanation see ntfs_truncate() in
+ * fs/ntfs/inode.c.
+ *
+ * @cached_page and @lru_pvec are just optimizations for dealing with multiple
+ * pages.
+ *
+ * Return 0 on success and -errno on error.  In the case that an error is
+ * encountered it is possible that the initialized size will already have been
+ * incremented some way towards @new_init_size but it is guaranteed that if
+ * this is the case, the necessary zeroing will also have happened and that all
+ * metadata is self-consistent.
+ *
+ * Locking: i_mutex on the vfs inode corrseponsind to the ntfs inode @ni must be
+ *         held by the caller.
+ */
+static int ntfs_attr_extend_initialized(ntfs_inode *ni, const s64 new_init_size,
+               struct page **cached_page, struct pagevec *lru_pvec)
+{
+       s64 old_init_size;
+       loff_t old_i_size;
+       pgoff_t index, end_index;
+       unsigned long flags;
+       struct inode *vi = VFS_I(ni);
+       ntfs_inode *base_ni;
+       MFT_RECORD *m = NULL;
+       ATTR_RECORD *a;
+       ntfs_attr_search_ctx *ctx = NULL;
+       struct address_space *mapping;
+       struct page *page = NULL;
+       u8 *kattr;
+       int err;
+       u32 attr_len;
+
+       read_lock_irqsave(&ni->size_lock, flags);
+       old_init_size = ni->initialized_size;
+       old_i_size = i_size_read(vi);
+       BUG_ON(new_init_size > ni->allocated_size);
+       read_unlock_irqrestore(&ni->size_lock, flags);
+       ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
+                       "old_initialized_size 0x%llx, "
+                       "new_initialized_size 0x%llx, i_size 0x%llx.",
+                       vi->i_ino, (unsigned)le32_to_cpu(ni->type),
+                       (unsigned long long)old_init_size,
+                       (unsigned long long)new_init_size, old_i_size);
+       if (!NInoAttr(ni))
+               base_ni = ni;
+       else
+               base_ni = ni->ext.base_ntfs_ino;
+       /* Use goto to reduce indentation and we need the label below anyway. */
+       if (NInoNonResident(ni))
+               goto do_non_resident_extend;
+       BUG_ON(old_init_size != old_i_size);
+       m = map_mft_record(base_ni);
+       if (IS_ERR(m)) {
+               err = PTR_ERR(m);
+               m = NULL;
+               goto err_out;
+       }
+       ctx = ntfs_attr_get_search_ctx(base_ni, m);
+       if (unlikely(!ctx)) {
+               err = -ENOMEM;
+               goto err_out;
+       }
+       err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+                       CASE_SENSITIVE, 0, NULL, 0, ctx);
+       if (unlikely(err)) {
+               if (err == -ENOENT)
+                       err = -EIO;
+               goto err_out;
+       }
+       m = ctx->mrec;
+       a = ctx->attr;
+       BUG_ON(a->non_resident);
+       /* The total length of the attribute value. */
+       attr_len = le32_to_cpu(a->data.resident.value_length);
+       BUG_ON(old_i_size != (loff_t)attr_len);
+       /*
+        * Do the zeroing in the mft record and update the attribute size in
+        * the mft record.
+        */
+       kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
+       memset(kattr + attr_len, 0, new_init_size - attr_len);
+       a->data.resident.value_length = cpu_to_le32((u32)new_init_size);
+       /* Finally, update the sizes in the vfs and ntfs inodes. */
+       write_lock_irqsave(&ni->size_lock, flags);
+       i_size_write(vi, new_init_size);
+       ni->initialized_size = new_init_size;
+       write_unlock_irqrestore(&ni->size_lock, flags);
+       goto done;
+do_non_resident_extend:
+       /*
+        * If the new initialized size @new_init_size exceeds the current file
+        * size (vfs inode->i_size), we need to extend the file size to the
+        * new initialized size.
+        */
+       if (new_init_size > old_i_size) {
+               m = map_mft_record(base_ni);
+               if (IS_ERR(m)) {
+                       err = PTR_ERR(m);
+                       m = NULL;
+                       goto err_out;
+               }
+               ctx = ntfs_attr_get_search_ctx(base_ni, m);
+               if (unlikely(!ctx)) {
+                       err = -ENOMEM;
+                       goto err_out;
+               }
+               err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+                               CASE_SENSITIVE, 0, NULL, 0, ctx);
+               if (unlikely(err)) {
+                       if (err == -ENOENT)
+                               err = -EIO;
+                       goto err_out;
+               }
+               m = ctx->mrec;
+               a = ctx->attr;
+               BUG_ON(!a->non_resident);
+               BUG_ON(old_i_size != (loff_t)
+                               sle64_to_cpu(a->data.non_resident.data_size));
+               a->data.non_resident.data_size = cpu_to_sle64(new_init_size);
+               flush_dcache_mft_record_page(ctx->ntfs_ino);
+               mark_mft_record_dirty(ctx->ntfs_ino);
+               /* Update the file size in the vfs inode. */
+               i_size_write(vi, new_init_size);
+               ntfs_attr_put_search_ctx(ctx);
+               ctx = NULL;
+               unmap_mft_record(base_ni);
+               m = NULL;
+       }
+       mapping = vi->i_mapping;
+       index = old_init_size >> PAGE_CACHE_SHIFT;
+       end_index = (new_init_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+       do {
+               /*
+                * Read the page.  If the page is not present, this will zero
+                * the uninitialized regions for us.
+                */
+               page = read_mapping_page(mapping, index, NULL);
+               if (IS_ERR(page)) {
+                       err = PTR_ERR(page);
+                       goto init_err_out;
+               }
+               if (unlikely(PageError(page))) {
+                       page_cache_release(page);
+                       err = -EIO;
+                       goto init_err_out;
+               }
+               /*
+                * Update the initialized size in the ntfs inode.  This is
+                * enough to make ntfs_writepage() work.
+                */
+               write_lock_irqsave(&ni->size_lock, flags);
+               ni->initialized_size = (s64)(index + 1) << PAGE_CACHE_SHIFT;
+               if (ni->initialized_size > new_init_size)
+                       ni->initialized_size = new_init_size;
+               write_unlock_irqrestore(&ni->size_lock, flags);
+               /* Set the page dirty so it gets written out. */
+               set_page_dirty(page);
+               page_cache_release(page);
+               /*
+                * Play nice with the vm and the rest of the system.  This is
+                * very much needed as we can potentially be modifying the
+                * initialised size from a very small value to a really huge
+                * value, e.g.
+                *      f = open(somefile, O_TRUNC);
+                *      truncate(f, 10GiB);
+                *      seek(f, 10GiB);
+                *      write(f, 1);
+                * And this would mean we would be marking dirty hundreds of
+                * thousands of pages or as in the above example more than
+                * two and a half million pages!
+                *
+                * TODO: For sparse pages could optimize this workload by using
+                * the FsMisc / MiscFs page bit as a "PageIsSparse" bit.  This
+                * would be set in readpage for sparse pages and here we would
+                * not need to mark dirty any pages which have this bit set.
+                * The only caveat is that we have to clear the bit everywhere
+                * where we allocate any clusters that lie in the page or that
+                * contain the page.
+                *
+                * TODO: An even greater optimization would be for us to only
+                * call readpage() on pages which are not in sparse regions as
+                * determined from the runlist.  This would greatly reduce the
+                * number of pages we read and make dirty in the case of sparse
+                * files.
+                */
+               balance_dirty_pages_ratelimited(mapping);
+               cond_resched();
+       } while (++index < end_index);
+       read_lock_irqsave(&ni->size_lock, flags);
+       BUG_ON(ni->initialized_size != new_init_size);
+       read_unlock_irqrestore(&ni->size_lock, flags);
+       /* Now bring in sync the initialized_size in the mft record. */
+       m = map_mft_record(base_ni);
+       if (IS_ERR(m)) {
+               err = PTR_ERR(m);
+               m = NULL;
+               goto init_err_out;
+       }
+       ctx = ntfs_attr_get_search_ctx(base_ni, m);
+       if (unlikely(!ctx)) {
+               err = -ENOMEM;
+               goto init_err_out;
+       }
+       err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+                       CASE_SENSITIVE, 0, NULL, 0, ctx);
+       if (unlikely(err)) {
+               if (err == -ENOENT)
+                       err = -EIO;
+               goto init_err_out;
+       }
+       m = ctx->mrec;
+       a = ctx->attr;
+       BUG_ON(!a->non_resident);
+       a->data.non_resident.initialized_size = cpu_to_sle64(new_init_size);
+done:
+       flush_dcache_mft_record_page(ctx->ntfs_ino);
+       mark_mft_record_dirty(ctx->ntfs_ino);
+       if (ctx)
+               ntfs_attr_put_search_ctx(ctx);
+       if (m)
+               unmap_mft_record(base_ni);
+       ntfs_debug("Done, initialized_size 0x%llx, i_size 0x%llx.",
+                       (unsigned long long)new_init_size, i_size_read(vi));
+       return 0;
+init_err_out:
+       write_lock_irqsave(&ni->size_lock, flags);
+       ni->initialized_size = old_init_size;
+       write_unlock_irqrestore(&ni->size_lock, flags);
+err_out:
+       if (ctx)
+               ntfs_attr_put_search_ctx(ctx);
+       if (m)
+               unmap_mft_record(base_ni);
+       ntfs_debug("Failed.  Returning error code %i.", err);
+       return err;
+}
+
+/**
+ * ntfs_fault_in_pages_readable -
+ *
+ * Fault a number of userspace pages into pagetables.
+ *
+ * Unlike include/linux/pagemap.h::fault_in_pages_readable(), this one copes
+ * with more than two userspace pages as well as handling the single page case
+ * elegantly.
+ *
+ * If you find this difficult to understand, then think of the while loop being
+ * the following code, except that we do without the integer variable ret:
+ *
+ *     do {
+ *             ret = __get_user(c, uaddr);
+ *             uaddr += PAGE_SIZE;
+ *     } while (!ret && uaddr < end);
+ *
+ * Note, the final __get_user() may well run out-of-bounds of the user buffer,
+ * but _not_ out-of-bounds of the page the user buffer belongs to, and since
+ * this is only a read and not a write, and since it is still in the same page,
+ * it should not matter and this makes the code much simpler.
+ */
+static inline void ntfs_fault_in_pages_readable(const char __user *uaddr,
+               int bytes)
+{
+       const char __user *end;
+       volatile char c;
+
+       /* Set @end to the first byte outside the last page we care about. */
+       end = (const char __user*)PAGE_ALIGN((unsigned long)uaddr + bytes);
+
+       while (!__get_user(c, uaddr) && (uaddr += PAGE_SIZE, uaddr < end))
+               ;
+}
+
+/**
+ * ntfs_fault_in_pages_readable_iovec -
+ *
+ * Same as ntfs_fault_in_pages_readable() but operates on an array of iovecs.
+ */
+static inline void ntfs_fault_in_pages_readable_iovec(const struct iovec *iov,
+               size_t iov_ofs, int bytes)
+{
+       do {
+               const char __user *buf;
+               unsigned len;
+
+               buf = iov->iov_base + iov_ofs;
+               len = iov->iov_len - iov_ofs;
+               if (len > bytes)
+                       len = bytes;
+               ntfs_fault_in_pages_readable(buf, len);
+               bytes -= len;
+               iov++;
+               iov_ofs = 0;
+       } while (bytes);
+}
+
+/**
+ * __ntfs_grab_cache_pages - obtain a number of locked pages
+ * @mapping:   address space mapping from which to obtain page cache pages
+ * @index:     starting index in @mapping at which to begin obtaining pages
+ * @nr_pages:  number of page cache pages to obtain
+ * @pages:     array of pages in which to return the obtained page cache pages
+ * @cached_page: allocated but as yet unused page
+ * @lru_pvec:  lru-buffering pagevec of caller
+ *
+ * Obtain @nr_pages locked page cache pages from the mapping @mapping and
+ * starting at index @index.
+ *
+ * If a page is newly created, increment its refcount and add it to the
+ * caller's lru-buffering pagevec @lru_pvec.
+ *
+ * This is the same as mm/filemap.c::__grab_cache_page(), except that @nr_pages
+ * are obtained at once instead of just one page and that 0 is returned on
+ * success and -errno on error.
+ *
+ * Note, the page locks are obtained in ascending page index order.
+ */
+static inline int __ntfs_grab_cache_pages(struct address_space *mapping,
+               pgoff_t index, const unsigned nr_pages, struct page **pages,
+               struct page **cached_page, struct pagevec *lru_pvec)
+{
+       int err, nr;
+
+       BUG_ON(!nr_pages);
+       err = nr = 0;
+       do {
+               pages[nr] = find_lock_page(mapping, index);
+               if (!pages[nr]) {
+                       if (!*cached_page) {
+                               *cached_page = page_cache_alloc(mapping);
+                               if (unlikely(!*cached_page)) {
+                                       err = -ENOMEM;
+                                       goto err_out;
+                               }
+                       }
+                       err = add_to_page_cache(*cached_page, mapping, index,
+                                       GFP_KERNEL);
+                       if (unlikely(err)) {
+                               if (err == -EEXIST)
+                                       continue;
+                               goto err_out;
+                       }
+                       pages[nr] = *cached_page;
+                       page_cache_get(*cached_page);
+                       if (unlikely(!pagevec_add(lru_pvec, *cached_page)))
+                               __pagevec_lru_add_file(lru_pvec);
+                       *cached_page = NULL;
+               }
+               index++;
+               nr++;
+       } while (nr < nr_pages);
+out:
+       return err;
+err_out:
+       while (nr > 0) {
+               unlock_page(pages[--nr]);
+               page_cache_release(pages[nr]);
+       }
+       goto out;
+}
+
+static inline int ntfs_submit_bh_for_read(struct buffer_head *bh)
+{
+       lock_buffer(bh);
+       get_bh(bh);
+       bh->b_end_io = end_buffer_read_sync;
+       return submit_bh(READ, bh);
+}
+
+/**
+ * ntfs_prepare_pages_for_non_resident_write - prepare pages for receiving data
+ * @pages:     array of destination pages
+ * @nr_pages:  number of pages in @pages
+ * @pos:       byte position in file at which the write begins
+ * @bytes:     number of bytes to be written
+ *
+ * This is called for non-resident attributes from ntfs_file_buffered_write()
+ * with i_mutex held on the inode (@pages[0]->mapping->host).  There are
+ * @nr_pages pages in @pages which are locked but not kmap()ped.  The source
+ * data has not yet been copied into the @pages.
+ * 
+ * Need to fill any holes with actual clusters, allocate buffers if necessary,
+ * ensure all the buffers are mapped, and bring uptodate any buffers that are
+ * only partially being written to.
+ *
+ * If @nr_pages is greater than one, we are guaranteed that the cluster size is
+ * greater than PAGE_CACHE_SIZE, that all pages in @pages are entirely inside
+ * the same cluster and that they are the entirety of that cluster, and that
+ * the cluster is sparse, i.e. we need to allocate a cluster to fill the hole.
+ *
+ * i_size is not to be modified yet.
+ *
+ * Return 0 on success or -errno on error.
+ */
+static int ntfs_prepare_pages_for_non_resident_write(struct page **pages,
+               unsigned nr_pages, s64 pos, size_t bytes)
+{
+       VCN vcn, highest_vcn = 0, cpos, cend, bh_cpos, bh_cend;
+       LCN lcn;
+       s64 bh_pos, vcn_len, end, initialized_size;
+       sector_t lcn_block;
+       struct page *page;
+       struct inode *vi;
+       ntfs_inode *ni, *base_ni = NULL;
+       ntfs_volume *vol;
+       runlist_element *rl, *rl2;
+       struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
+       ntfs_attr_search_ctx *ctx = NULL;
+       MFT_RECORD *m = NULL;
+       ATTR_RECORD *a = NULL;
+       unsigned long flags;
+       u32 attr_rec_len = 0;
+       unsigned blocksize, u;
+       int err, mp_size;
+       bool rl_write_locked, was_hole, is_retry;
+       unsigned char blocksize_bits;
+       struct {
+               u8 runlist_merged:1;
+               u8 mft_attr_mapped:1;
+               u8 mp_rebuilt:1;
+               u8 attr_switched:1;
+       } status = { 0, 0, 0, 0 };
+
+       BUG_ON(!nr_pages);
+       BUG_ON(!pages);
+       BUG_ON(!*pages);
+       vi = pages[0]->mapping->host;
+       ni = NTFS_I(vi);
+       vol = ni->vol;
+       ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
+                       "index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
+                       vi->i_ino, ni->type, pages[0]->index, nr_pages,
+                       (long long)pos, bytes);
+       blocksize = vol->sb->s_blocksize;
+       blocksize_bits = vol->sb->s_blocksize_bits;
+       u = 0;
+       do {
+               page = pages[u];
+               BUG_ON(!page);
+               /*
+                * create_empty_buffers() will create uptodate/dirty buffers if
+                * the page is uptodate/dirty.
+                */
+               if (!page_has_buffers(page)) {
+                       create_empty_buffers(page, blocksize, 0);
+                       if (unlikely(!page_has_buffers(page)))
+                               return -ENOMEM;
+               }
+       } while (++u < nr_pages);
+       rl_write_locked = false;
+       rl = NULL;
+       err = 0;
+       vcn = lcn = -1;
+       vcn_len = 0;
+       lcn_block = -1;
+       was_hole = false;
+       cpos = pos >> vol->cluster_size_bits;
+       end = pos + bytes;
+       cend = (end + vol->cluster_size - 1) >> vol->cluster_size_bits;
+       /*
+        * Loop over each page and for each page over each buffer.  Use goto to
+        * reduce indentation.
+        */
+       u = 0;
+do_next_page:
+       page = pages[u];
+       bh_pos = (s64)page->index << PAGE_CACHE_SHIFT;
+       bh = head = page_buffers(page);
+       do {
+               VCN cdelta;
+               s64 bh_end;
+               unsigned bh_cofs;
+
+               /* Clear buffer_new on all buffers to reinitialise state. */
+               if (buffer_new(bh))
+                       clear_buffer_new(bh);
+               bh_end = bh_pos + blocksize;
+               bh_cpos = bh_pos >> vol->cluster_size_bits;
+               bh_cofs = bh_pos & vol->cluster_size_mask;
+               if (buffer_mapped(bh)) {
+                       /*
+                        * The buffer is already mapped.  If it is uptodate,
+                        * ignore it.
+                        */
+                       if (buffer_uptodate(bh))
+                               continue;
+                       /*
+                        * The buffer is not uptodate.  If the page is uptodate
+                        * set the buffer uptodate and otherwise ignore it.
+                        */
+                       if (PageUptodate(page)) {
+                               set_buffer_uptodate(bh);
+                               continue;
+                       }
+                       /*
+                        * Neither the page nor the buffer are uptodate.  If
+                        * the buffer is only partially being written to, we
+                        * need to read it in before the write, i.e. now.
+                        */
+                       if ((bh_pos < pos && bh_end > pos) ||
+                                       (bh_pos < end && bh_end > end)) {
+                               /*
+                                * If the buffer is fully or partially within
+                                * the initialized size, do an actual read.
+                                * Otherwise, simply zero the buffer.
+                                */
+                               read_lock_irqsave(&ni->size_lock, flags);
+                               initialized_size = ni->initialized_size;
+                               read_unlock_irqrestore(&ni->size_lock, flags);
+                               if (bh_pos < initialized_size) {
+                                       ntfs_submit_bh_for_read(bh);
+                                       *wait_bh++ = bh;
+                               } else {
+                                       zero_user(page, bh_offset(bh),
+                                                       blocksize);
+                                       set_buffer_uptodate(bh);
+                               }
+                       }
+                       continue;
+               }
+               /* Unmapped buffer.  Need to map it. */
+               bh->b_bdev = vol->sb->s_bdev;
+               /*
+                * If the current buffer is in the same clusters as the map
+                * cache, there is no need to check the runlist again.  The
+                * map cache is made up of @vcn, which is the first cached file
+                * cluster, @vcn_len which is the number of cached file
+                * clusters, @lcn is the device cluster corresponding to @vcn,
+                * and @lcn_block is the block number corresponding to @lcn.
+                */
+               cdelta = bh_cpos - vcn;
+               if (likely(!cdelta || (cdelta > 0 && cdelta < vcn_len))) {
+map_buffer_cached:
+                       BUG_ON(lcn < 0);
+                       bh->b_blocknr = lcn_block +
+                                       (cdelta << (vol->cluster_size_bits -
+                                       blocksize_bits)) +
+                                       (bh_cofs >> blocksize_bits);
+                       set_buffer_mapped(bh);
+                       /*
+                        * If the page is uptodate so is the buffer.  If the
+                        * buffer is fully outside the write, we ignore it if
+                        * it was already allocated and we mark it dirty so it
+                        * gets written out if we allocated it.  On the other
+                        * hand, if we allocated the buffer but we are not
+                        * marking it dirty we set buffer_new so we can do
+                        * error recovery.
+                        */
+                       if (PageUptodate(page)) {
+                               if (!buffer_uptodate(bh))
+                                       set_buffer_uptodate(bh);
+                               if (unlikely(was_hole)) {
+                                       /* We allocated the buffer. */
+                                       unmap_underlying_metadata(bh->b_bdev,
+                                                       bh->b_blocknr);
+                                       if (bh_end <= pos || bh_pos >= end)
+                                               mark_buffer_dirty(bh);
+                                       else
+                                               set_buffer_new(bh);
+                               }
+                               continue;
+                       }
+                       /* Page is _not_ uptodate. */
+                       if (likely(!was_hole)) {
+                               /*
+                                * Buffer was already allocated.  If it is not
+                                * uptodate and is only partially being written
+                                * to, we need to read it in before the write,
+                                * i.e. now.
+                                */
+                               if (!buffer_uptodate(bh) && bh_pos < end &&
+                                               bh_end > pos &&
+                                               (bh_pos < pos ||
+                                               bh_end > end)) {
+                                       /*
+                                        * If the buffer is fully or partially
+                                        * within the initialized size, do an
+                                        * actual read.  Otherwise, simply zero
+                                        * the buffer.
+                                        */
+                                       read_lock_irqsave(&ni->size_lock,
+                                                       flags);
+                                       initialized_size = ni->initialized_size;
+                                       read_unlock_irqrestore(&ni->size_lock,
+                                                       flags);
+                                       if (bh_pos < initialized_size) {
+                                               ntfs_submit_bh_for_read(bh);
+                                               *wait_bh++ = bh;
+                                       } else {
+                                               zero_user(page, bh_offset(bh),
+                                                               blocksize);
+                                               set_buffer_uptodate(bh);
+                                       }
+                               }
+                               continue;
+                       }
+                       /* We allocated the buffer. */
+                       unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
+                       /*
+                        * If the buffer is fully outside the write, zero it,
+                        * set it uptodate, and mark it dirty so it gets
+                        * written out.  If it is partially being written to,
+                        * zero region surrounding the write but leave it to
+                        * commit write to do anything else.  Finally, if the
+                        * buffer is fully being overwritten, do nothing.
+                        */
+                       if (bh_end <= pos || bh_pos >= end) {
+                               if (!buffer_uptodate(bh)) {
+                                       zero_user(page, bh_offset(bh),
+                                                       blocksize);
+                                       set_buffer_uptodate(bh);
+                               }
+                               mark_buffer_dirty(bh);
+                               continue;
+                       }
+                       set_buffer_new(bh);
+                       if (!buffer_uptodate(bh) &&
+                                       (bh_pos < pos || bh_end > end)) {
+                               u8 *kaddr;
+                               unsigned pofs;
+                                       
+                               kaddr = kmap_atomic(page, KM_USER0);
+                               if (bh_pos < pos) {
+                                       pofs = bh_pos & ~PAGE_CACHE_MASK;
+                                       memset(kaddr + pofs, 0, pos - bh_pos);
+                               }
+                               if (bh_end > end) {
+                                       pofs = end & ~PAGE_CACHE_MASK;
+                                       memset(kaddr + pofs, 0, bh_end - end);
+                               }
+                               kunmap_atomic(kaddr, KM_USER0);
+                               flush_dcache_page(page);
+                       }
+                       continue;
+               }
+               /*
+                * Slow path: this is the first buffer in the cluster.  If it
+                * is outside allocated size and is not uptodate, zero it and
+                * set it uptodate.
+                */
+               read_lock_irqsave(&ni->size_lock, flags);
+               initialized_size = ni->allocated_size;
+               read_unlock_irqrestore(&ni->size_lock, flags);
+               if (bh_pos > initialized_size) {
+                       if (PageUptodate(page)) {
+                               if (!buffer_uptodate(bh))
+                                       set_buffer_uptodate(bh);
+                       } else if (!buffer_uptodate(bh)) {
+                               zero_user(page, bh_offset(bh), blocksize);
+                               set_buffer_uptodate(bh);
+                       }
+                       continue;
+               }
+               is_retry = false;
+               if (!rl) {
+                       down_read(&ni->runlist.lock);
+retry_remap:
+                       rl = ni->runlist.rl;
+               }
+               if (likely(rl != NULL)) {
+                       /* Seek to element containing target cluster. */
+                       while (rl->length && rl[1].vcn <= bh_cpos)
+                               rl++;
+                       lcn = ntfs_rl_vcn_to_lcn(rl, bh_cpos);
+                       if (likely(lcn >= 0)) {
+                               /*
+                                * Successful remap, setup the map cache and
+                                * use that to deal with the buffer.
+                                */
+                               was_hole = false;
+                               vcn = bh_cpos;
+                               vcn_len = rl[1].vcn - vcn;
+                               lcn_block = lcn << (vol->cluster_size_bits -
+                                               blocksize_bits);
+                               cdelta = 0;
+                               /*
+                                * If the number of remaining clusters touched
+                                * by the write is smaller or equal to the
+                                * number of cached clusters, unlock the
+                                * runlist as the map cache will be used from
+                                * now on.
+                                */
+                               if (likely(vcn + vcn_len >= cend)) {
+                                       if (rl_write_locked) {
+                                               up_write(&ni->runlist.lock);
+                                               rl_write_locked = false;
+                                       } else
+                                               up_read(&ni->runlist.lock);
+                                       rl = NULL;
+                               }
+                               goto map_buffer_cached;
+                       }
+               } else
+                       lcn = LCN_RL_NOT_MAPPED;
+               /*
+                * If it is not a hole and not out of bounds, the runlist is
+                * probably unmapped so try to map it now.
+                */
+               if (unlikely(lcn != LCN_HOLE && lcn != LCN_ENOENT)) {
+                       if (likely(!is_retry && lcn == LCN_RL_NOT_MAPPED)) {
+                               /* Attempt to map runlist. */
+                               if (!rl_write_locked) {
+                                       /*
+                                        * We need the runlist locked for
+                                        * writing, so if it is locked for
+                                        * reading relock it now and retry in
+                                        * case it changed whilst we dropped
+                                        * the lock.
+                                        */
+                                       up_read(&ni->runlist.lock);
+                                       down_write(&ni->runlist.lock);
+                                       rl_write_locked = true;
+                                       goto retry_remap;
+                               }
+                               err = ntfs_map_runlist_nolock(ni, bh_cpos,
+                                               NULL);
+                               if (likely(!err)) {
+                                       is_retry = true;
+                                       goto retry_remap;
+                               }
+                               /*
+                                * If @vcn is out of bounds, pretend @lcn is
+                                * LCN_ENOENT.  As long as the buffer is out
+                                * of bounds this will work fine.
+                                */
+                               if (err == -ENOENT) {
+                                       lcn = LCN_ENOENT;
+                                       err = 0;
+                                       goto rl_not_mapped_enoent;
+                               }
+                       } else
+                               err = -EIO;
+                       /* Failed to map the buffer, even after retrying. */
+                       bh->b_blocknr = -1;
+                       ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
+                                       "attribute type 0x%x, vcn 0x%llx, "
+                                       "vcn offset 0x%x, because its "
+                                       "location on disk could not be "
+                                       "determined%s (error code %i).",
+                                       ni->mft_no, ni->type,
+                                       (unsigned long long)bh_cpos,
+                                       (unsigned)bh_pos &
+                                       vol->cluster_size_mask,
+                                       is_retry ? " even after retrying" : "",
+                                       err);
+                       break;
+               }
+rl_not_mapped_enoent:
+               /*
+                * The buffer is in a hole or out of bounds.  We need to fill
+                * the hole, unless the buffer is in a cluster which is not
+                * touched by the write, in which case we just leave the buffer
+                * unmapped.  This can only happen when the cluster size is
+                * less than the page cache size.
+                */
+               if (unlikely(vol->cluster_size < PAGE_CACHE_SIZE)) {
+                       bh_cend = (bh_end + vol->cluster_size - 1) >>
+                                       vol->cluster_size_bits;
+                       if ((bh_cend <= cpos || bh_cpos >= cend)) {
+                               bh->b_blocknr = -1;
+                               /*
+                                * If the buffer is uptodate we skip it.  If it
+                                * is not but the page is uptodate, we can set
+                                * the buffer uptodate.  If the page is not
+                                * uptodate, we can clear the buffer and set it
+                                * uptodate.  Whether this is worthwhile is
+                                * debatable and this could be removed.
+                                */
+                               if (PageUptodate(page)) {
+                                       if (!buffer_uptodate(bh))
+                                               set_buffer_uptodate(bh);
+                               } else if (!buffer_uptodate(bh)) {
+                                       zero_user(page, bh_offset(bh),
+                                               blocksize);
+                                       set_buffer_uptodate(bh);
+                               }
+                               continue;
+                       }
+               }
+               /*
+                * Out of bounds buffer is invalid if it was not really out of
+                * bounds.
+                */
+               BUG_ON(lcn != LCN_HOLE);
+               /*
+                * We need the runlist locked for writing, so if it is locked
+                * for reading relock it now and retry in case it changed
+                * whilst we dropped the lock.
+                */
+               BUG_ON(!rl);
+               if (!rl_write_locked) {
+                       up_read(&ni->runlist.lock);
+                       down_write(&ni->runlist.lock);
+                       rl_write_locked = true;
+                       goto retry_remap;
+               }
+               /* Find the previous last allocated cluster. */
+               BUG_ON(rl->lcn != LCN_HOLE);
+               lcn = -1;
+               rl2 = rl;
+               while (--rl2 >= ni->runlist.rl) {
+                       if (rl2->lcn >= 0) {
+                               lcn = rl2->lcn + rl2->length;
+                               break;
+                       }
+               }
+               rl2 = ntfs_cluster_alloc(vol, bh_cpos, 1, lcn, DATA_ZONE,
+                               false);
+               if (IS_ERR(rl2)) {
+                       err = PTR_ERR(rl2);
+                       ntfs_debug("Failed to allocate cluster, error code %i.",
+                                       err);
+                       break;
+               }
+               lcn = rl2->lcn;
+               rl = ntfs_runlists_merge(ni->runlist.rl, rl2);
+               if (IS_ERR(rl)) {
+                       err = PTR_ERR(rl);
+                       if (err != -ENOMEM)
+                               err = -EIO;
+                       if (ntfs_cluster_free_from_rl(vol, rl2)) {
+                               ntfs_error(vol->sb, "Failed to release "
+                                               "allocated cluster in error "
+                                               "code path.  Run chkdsk to "
+                                               "recover the lost cluster.");
+                               NVolSetErrors(vol);
+                       }
+                       ntfs_free(rl2);
+                       break;
+               }
+               ni->runlist.rl = rl;
+               status.runlist_merged = 1;
+               ntfs_debug("Allocated cluster, lcn 0x%llx.",
+                               (unsigned long long)lcn);
+               /* Map and lock the mft record and get the attribute record. */
+               if (!NInoAttr(ni))
+                       base_ni = ni;
+               else
+                       base_ni = ni->ext.base_ntfs_ino;
+               m = map_mft_record(base_ni);
+               if (IS_ERR(m)) {
+                       err = PTR_ERR(m);
+                       break;
+               }
+               ctx = ntfs_attr_get_search_ctx(base_ni, m);
+               if (unlikely(!ctx)) {
+                       err = -ENOMEM;
+                       unmap_mft_record(base_ni);
+                       break;
+               }
+               status.mft_attr_mapped = 1;
+               err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+                               CASE_SENSITIVE, bh_cpos, NULL, 0, ctx);
+               if (unlikely(err)) {
+                       if (err == -ENOENT)
+                               err = -EIO;
+                       break;
+               }
+               m = ctx->mrec;
+               a = ctx->attr;
+               /*
+                * Find the runlist element with which the attribute extent
+                * starts.  Note, we cannot use the _attr_ version because we
+                * have mapped the mft record.  That is ok because we know the
+                * runlist fragment must be mapped already to have ever gotten
+                * here, so we can just use the _rl_ version.
+                */
+               vcn = sle64_to_cpu(a->data.non_resident.lowest_vcn);
+               rl2 = ntfs_rl_find_vcn_nolock(rl, vcn);
+               BUG_ON(!rl2);
+               BUG_ON(!rl2->length);
+               BUG_ON(rl2->lcn < LCN_HOLE);
+               highest_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn);
+               /*
+                * If @highest_vcn is zero, calculate the real highest_vcn
+                * (which can really be zero).
+                */
+               if (!highest_vcn)
+                       highest_vcn = (sle64_to_cpu(
+                                       a->data.non_resident.allocated_size) >>
+                                       vol->cluster_size_bits) - 1;
+               /*
+                * Determine the size of the mapping pairs array for the new
+                * extent, i.e. the old extent with the hole filled.
+                */
+               mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, vcn,
+                               highest_vcn);
+               if (unlikely(mp_size <= 0)) {
+                       if (!(err = mp_size))
+                               err = -EIO;
+                       ntfs_debug("Failed to get size for mapping pairs "
+                                       "array, error code %i.", err);
+                       break;
+               }
+               /*
+                * Resize the attribute record to fit the new mapping pairs
+                * array.
+                */
+               attr_rec_len = le32_to_cpu(a->length);
+               err = ntfs_attr_record_resize(m, a, mp_size + le16_to_cpu(
+                               a->data.non_resident.mapping_pairs_offset));
+               if (unlikely(err)) {
+                       BUG_ON(err != -ENOSPC);
+                       // TODO: Deal with this by using the current attribute
+                       // and fill it with as much of the mapping pairs
+                       // array as possible.  Then loop over each attribute
+                       // extent rewriting the mapping pairs arrays as we go
+                       // along and if when we reach the end we have not
+                       // enough space, try to resize the last attribute
+                       // extent and if even that fails, add a new attribute
+                       // extent.
+                       // We could also try to resize at each step in the hope
+                       // that we will not need to rewrite every single extent.
+                       // Note, we may need to decompress some extents to fill
+                       // the runlist as we are walking the extents...
+                       ntfs_error(vol->sb, "Not enough space in the mft "
+                                       "record for the extended attribute "
+                                       "record.  This case is not "
+                                       "implemented yet.");
+                       err = -EOPNOTSUPP;
+                       break ;
+               }
+               status.mp_rebuilt = 1;
+               /*
+                * Generate the mapping pairs array directly into the attribute
+                * record.
+                */
+               err = ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
+                               a->data.non_resident.mapping_pairs_offset),
+                               mp_size, rl2, vcn, highest_vcn, NULL);
+               if (unlikely(err)) {
+                       ntfs_error(vol->sb, "Cannot fill hole in inode 0x%lx, "
+                                       "attribute type 0x%x, because building "
+                                       "the mapping pairs failed with error "
+                                       "code %i.", vi->i_ino,
+                                       (unsigned)le32_to_cpu(ni->type), err);
+                       err = -EIO;
+                       break;
+               }
+               /* Update the highest_vcn but only if it was not set. */
+               if (unlikely(!a->data.non_resident.highest_vcn))
+                       a->data.non_resident.highest_vcn =
+                                       cpu_to_sle64(highest_vcn);
+               /*
+                * If the attribute is sparse/compressed, update the compressed
+                * size in the ntfs_inode structure and the attribute record.
+                */
+               if (likely(NInoSparse(ni) || NInoCompressed(ni))) {
+                       /*
+                        * If we are not in the first attribute extent, switch
+                        * to it, but first ensure the changes will make it to
+                        * disk later.
+                        */
+                       if (a->data.non_resident.lowest_vcn) {
+                               flush_dcache_mft_record_page(ctx->ntfs_ino);
+                               mark_mft_record_dirty(ctx->ntfs_ino);
+                               ntfs_attr_reinit_search_ctx(ctx);
+                               err = ntfs_attr_lookup(ni->type, ni->name,
+                                               ni->name_len, CASE_SENSITIVE,
+                                               0, NULL, 0, ctx);
+                               if (unlikely(err)) {
+                                       status.attr_switched = 1;
+                                       break;
+                               }
+                               /* @m is not used any more so do not set it. */
+                               a = ctx->attr;
+                       }
+                       write_lock_irqsave(&ni->size_lock, flags);
+                       ni->itype.compressed.size += vol->cluster_size;
+                       a->data.non_resident.compressed_size =
+                                       cpu_to_sle64(ni->itype.compressed.size);
+                       write_unlock_irqrestore(&ni->size_lock, flags);
+               }
+               /* Ensure the changes make it to disk. */
+               flush_dcache_mft_record_page(ctx->ntfs_ino);
+               mark_mft_record_dirty(ctx->ntfs_ino);
+               ntfs_attr_put_search_ctx(ctx);
+               unmap_mft_record(base_ni);
+               /* Successfully filled the hole. */
+               status.runlist_merged = 0;
+               status.mft_attr_mapped = 0;
+               status.mp_rebuilt = 0;
+               /* Setup the map cache and use that to deal with the buffer. */
+               was_hole = true;
+               vcn = bh_cpos;
+               vcn_len = 1;
+               lcn_block = lcn << (vol->cluster_size_bits - blocksize_bits);
+               cdelta = 0;
+               /*
+                * If the number of remaining clusters in the @pages is smaller
+                * or equal to the number of cached clusters, unlock the
+                * runlist as the map cache will be used from now on.
+                */
+               if (likely(vcn + vcn_len >= cend)) {
+                       up_write(&ni->runlist.lock);
+                       rl_write_locked = false;
+                       rl = NULL;
+               }
+               goto map_buffer_cached;
+       } while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
+       /* If there are no errors, do the next page. */
+       if (likely(!err && ++u < nr_pages))
+               goto do_next_page;
+       /* If there are no errors, release the runlist lock if we took it. */
+       if (likely(!err)) {
+               if (unlikely(rl_write_locked)) {
+                       up_write(&ni->runlist.lock);
+                       rl_write_locked = false;
+               } else if (unlikely(rl))
+                       up_read(&ni->runlist.lock);
+               rl = NULL;
+       }
+       /* If we issued read requests, let them complete. */
+       read_lock_irqsave(&ni->size_lock, flags);
+       initialized_size = ni->initialized_size;
+       read_unlock_irqrestore(&ni->size_lock, flags);
+       while (wait_bh > wait) {
+               bh = *--wait_bh;
+               wait_on_buffer(bh);
+               if (likely(buffer_uptodate(bh))) {
+                       page = bh->b_page;
+                       bh_pos = ((s64)page->index << PAGE_CACHE_SHIFT) +
+                                       bh_offset(bh);
+                       /*
+                        * If the buffer overflows the initialized size, need
+                        * to zero the overflowing region.
+                        */
+                       if (unlikely(bh_pos + blocksize > initialized_size)) {
+                               int ofs = 0;
+
+                               if (likely(bh_pos < initialized_size))
+                                       ofs = initialized_size - bh_pos;
+                               zero_user_segment(page, bh_offset(bh) + ofs,
+                                               blocksize);
+                       }
+               } else /* if (unlikely(!buffer_uptodate(bh))) */
+                       err = -EIO;
+       }
+       if (likely(!err)) {
+               /* Clear buffer_new on all buffers. */
+               u = 0;
+               do {
+                       bh = head = page_buffers(pages[u]);
+                       do {
+                               if (buffer_new(bh))
+                                       clear_buffer_new(bh);
+                       } while ((bh = bh->b_this_page) != head);
+               } while (++u < nr_pages);
+               ntfs_debug("Done.");
+               return err;
+       }
+       if (status.attr_switched) {
+               /* Get back to the attribute extent we modified. */
+               ntfs_attr_reinit_search_ctx(ctx);
+               if (ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+                               CASE_SENSITIVE, bh_cpos, NULL, 0, ctx)) {
+                       ntfs_error(vol->sb, "Failed to find required "
+                                       "attribute extent of attribute in "
+                                       "error code path.  Run chkdsk to "
+                                       "recover.");
+                       write_lock_irqsave(&ni->size_lock, flags);
+                       ni->itype.compressed.size += vol->cluster_size;
+                       write_unlock_irqrestore(&ni->size_lock, flags);
+                       flush_dcache_mft_record_page(ctx->ntfs_ino);
+                       mark_mft_record_dirty(ctx->ntfs_ino);
+                       /*
+                        * The only thing that is now wrong is the compressed
+                        * size of the base attribute extent which chkdsk
+                        * should be able to fix.
+                        */
+                       NVolSetErrors(vol);
+               } else {
+                       m = ctx->mrec;
+                       a = ctx->attr;
+                       status.attr_switched = 0;
+               }
+       }
+       /*
+        * If the runlist has been modified, need to restore it by punching a
+        * hole into it and we then need to deallocate the on-disk cluster as
+        * well.  Note, we only modify the runlist if we are able to generate a
+        * new mapping pairs array, i.e. only when the mapped attribute extent
+        * is not switched.
+        */
+       if (status.runlist_merged && !status.attr_switched) {
+               BUG_ON(!rl_write_locked);
+               /* Make the file cluster we allocated sparse in the runlist. */
+               if (ntfs_rl_punch_nolock(vol, &ni->runlist, bh_cpos, 1)) {
+                       ntfs_error(vol->sb, "Failed to punch hole into "
+                                       "attribute runlist in error code "
+                                       "path.  Run chkdsk to recover the "
+                                       "lost cluster.");
+                       NVolSetErrors(vol);
+               } else /* if (success) */ {
+                       status.runlist_merged = 0;
+                       /*
+                        * Deallocate the on-disk cluster we allocated but only
+                        * if we succeeded in punching its vcn out of the
+                        * runlist.
+                        */
+                       down_write(&vol->lcnbmp_lock);
+                       if (ntfs_bitmap_clear_bit(vol->lcnbmp_ino, lcn)) {
+                               ntfs_error(vol->sb, "Failed to release "
+                                               "allocated cluster in error "
+                                               "code path.  Run chkdsk to "
+                                               "recover the lost cluster.");
+                               NVolSetErrors(vol);
+                       }
+                       up_write(&vol->lcnbmp_lock);
+               }
+       }
+       /*
+        * Resize the attribute record to its old size and rebuild the mapping
+        * pairs array.  Note, we only can do this if the runlist has been
+        * restored to its old state which also implies that the mapped
+        * attribute extent is not switched.
+        */
+       if (status.mp_rebuilt && !status.runlist_merged) {
+               if (ntfs_attr_record_resize(m, a, attr_rec_len)) {
+                       ntfs_error(vol->sb, "Failed to restore attribute "
+                                       "record in error code path.  Run "
+                                       "chkdsk to recover.");
+                       NVolSetErrors(vol);
+               } else /* if (success) */ {
+                       if (ntfs_mapping_pairs_build(vol, (u8*)a +
+                                       le16_to_cpu(a->data.non_resident.
+                                       mapping_pairs_offset), attr_rec_len -
+                                       le16_to_cpu(a->data.non_resident.
+                                       mapping_pairs_offset), ni->runlist.rl,
+                                       vcn, highest_vcn, NULL)) {
+                               ntfs_error(vol->sb, "Failed to restore "
+                                               "mapping pairs array in error "
+                                               "code path.  Run chkdsk to "
+                                               "recover.");
+                               NVolSetErrors(vol);
+                       }
+                       flush_dcache_mft_record_page(ctx->ntfs_ino);
+                       mark_mft_record_dirty(ctx->ntfs_ino);
+               }
+       }
+       /* Release the mft record and the attribute. */
+       if (status.mft_attr_mapped) {
+               ntfs_attr_put_search_ctx(ctx);
+               unmap_mft_record(base_ni);
+       }
+       /* Release the runlist lock. */
+       if (rl_write_locked)
+               up_write(&ni->runlist.lock);
+       else if (rl)
+               up_read(&ni->runlist.lock);
+       /*
+        * Zero out any newly allocated blocks to avoid exposing stale data.
+        * If BH_New is set, we know that the block was newly allocated above
+        * and that it has not been fully zeroed and marked dirty yet.
+        */
+       nr_pages = u;
+       u = 0;
+       end = bh_cpos << vol->cluster_size_bits;
+       do {
+               page = pages[u];
+               bh = head = page_buffers(page);
+               do {
+                       if (u == nr_pages &&
+                                       ((s64)page->index << PAGE_CACHE_SHIFT) +
+                                       bh_offset(bh) >= end)
+                               break;
+                       if (!buffer_new(bh))
+                               continue;
+                       clear_buffer_new(bh);
+                       if (!buffer_uptodate(bh)) {
+                               if (PageUptodate(page))
+                                       set_buffer_uptodate(bh);
+                               else {
+                                       zero_user(page, bh_offset(bh),
+                                                       blocksize);
+                                       set_buffer_uptodate(bh);
+                               }
+                       }
+                       mark_buffer_dirty(bh);
+               } while ((bh = bh->b_this_page) != head);
+       } while (++u <= nr_pages);
+       ntfs_error(vol->sb, "Failed.  Returning error code %i.", err);
+       return err;
+}
+
+/*
+ * Copy as much as we can into the pages and return the number of bytes which
+ * were successfully copied.  If a fault is encountered then clear the pages
+ * out to (ofs + bytes) and return the number of bytes which were copied.
+ */
+static inline size_t ntfs_copy_from_user(struct page **pages,
+               unsigned nr_pages, unsigned ofs, const char __user *buf,
+               size_t bytes)
+{
+       struct page **last_page = pages + nr_pages;
+       char *addr;
+       size_t total = 0;
+       unsigned len;
+       int left;
+
+       do {
+               len = PAGE_CACHE_SIZE - ofs;
+               if (len > bytes)
+                       len = bytes;
+               addr = kmap_atomic(*pages, KM_USER0);
+               left = __copy_from_user_inatomic(addr + ofs, buf, len);
+               kunmap_atomic(addr, KM_USER0);
+               if (unlikely(left)) {
+                       /* Do it the slow way. */
+                       addr = kmap(*pages);
+                       left = __copy_from_user(addr + ofs, buf, len);
+                       kunmap(*pages);
+                       if (unlikely(left))
+                               goto err_out;
+               }
+               total += len;
+               bytes -= len;
+               if (!bytes)
+                       break;
+               buf += len;
+               ofs = 0;
+       } while (++pages < last_page);
+out:
+       return total;
+err_out:
+       total += len - left;
+       /* Zero the rest of the target like __copy_from_user(). */
+       while (++pages < last_page) {
+               bytes -= len;
+               if (!bytes)
+                       break;
+               len = PAGE_CACHE_SIZE;
+               if (len > bytes)
+                       len = bytes;
+               zero_user(*pages, 0, len);
+       }
+       goto out;
+}
+
+static size_t __ntfs_copy_from_user_iovec_inatomic(char *vaddr,
+               const struct iovec *iov, size_t iov_ofs, size_t bytes)
+{
+       size_t total = 0;
+
+       while (1) {
+               const char __user *buf = iov->iov_base + iov_ofs;
+               unsigned len;
+               size_t left;
+
+               len = iov->iov_len - iov_ofs;
+               if (len > bytes)
+                       len = bytes;
+               left = __copy_from_user_inatomic(vaddr, buf, len);
+               total += len;
+               bytes -= len;
+               vaddr += len;
+               if (unlikely(left)) {
+                       total -= left;
+                       break;
+               }
+               if (!bytes)
+                       break;
+               iov++;
+               iov_ofs = 0;
+       }
+       return total;
+}
+
+static inline void ntfs_set_next_iovec(const struct iovec **iovp,
+               size_t *iov_ofsp, size_t bytes)
+{
+       const struct iovec *iov = *iovp;
+       size_t iov_ofs = *iov_ofsp;
+
+       while (bytes) {
+               unsigned len;
+
+               len = iov->iov_len - iov_ofs;
+               if (len > bytes)
+                       len = bytes;
+               bytes -= len;
+               iov_ofs += len;
+               if (iov->iov_len == iov_ofs) {
+                       iov++;
+                       iov_ofs = 0;
+               }
+       }
+       *iovp = iov;
+       *iov_ofsp = iov_ofs;
+}
+
+/*
+ * This has the same side-effects and return value as ntfs_copy_from_user().
+ * The difference is that on a fault we need to memset the remainder of the
+ * pages (out to offset + bytes), to emulate ntfs_copy_from_user()'s
+ * single-segment behaviour.
+ *
+ * We call the same helper (__ntfs_copy_from_user_iovec_inatomic()) both
+ * when atomic and when not atomic.  This is ok because
+ * __ntfs_copy_from_user_iovec_inatomic() calls __copy_from_user_inatomic()
+ * and it is ok to call this when non-atomic.
+ * Infact, the only difference between __copy_from_user_inatomic() and
+ * __copy_from_user() is that the latter calls might_sleep() and the former
+ * should not zero the tail of the buffer on error.  And on many
+ * architectures __copy_from_user_inatomic() is just defined to
+ * __copy_from_user() so it makes no difference at all on those architectures.
+ */
+static inline size_t ntfs_copy_from_user_iovec(struct page **pages,
+               unsigned nr_pages, unsigned ofs, const struct iovec **iov,
+               size_t *iov_ofs, size_t bytes)
+{
+       struct page **last_page = pages + nr_pages;
+       char *addr;
+       size_t copied, len, total = 0;
+
+       do {
+               len = PAGE_CACHE_SIZE - ofs;
+               if (len > bytes)
+                       len = bytes;
+               addr = kmap_atomic(*pages, KM_USER0);
+               copied = __ntfs_copy_from_user_iovec_inatomic(addr + ofs,
+                               *iov, *iov_ofs, len);
+               kunmap_atomic(addr, KM_USER0);
+               if (unlikely(copied != len)) {
+                       /* Do it the slow way. */
+                       addr = kmap(*pages);
+                       copied = __ntfs_copy_from_user_iovec_inatomic(addr + ofs,
+                                       *iov, *iov_ofs, len);
+                       /*
+                        * Zero the rest of the target like __copy_from_user().
+                        */
+                       memset(addr + ofs + copied, 0, len - copied);
+                       kunmap(*pages);
+                       if (unlikely(copied != len))
+                               goto err_out;
+               }
+               total += len;
+               bytes -= len;
+               if (!bytes)
+                       break;
+               ntfs_set_next_iovec(iov, iov_ofs, len);
+               ofs = 0;
+       } while (++pages < last_page);
+out:
+       return total;
+err_out:
+       total += copied;
+       /* Zero the rest of the target like __copy_from_user(). */
+       while (++pages < last_page) {
+               bytes -= len;
+               if (!bytes)
+                       break;
+               len = PAGE_CACHE_SIZE;
+               if (len > bytes)
+                       len = bytes;
+               zero_user(*pages, 0, len);
+       }
+       goto out;
+}
+
+static inline void ntfs_flush_dcache_pages(struct page **pages,
+               unsigned nr_pages)
+{
+       BUG_ON(!nr_pages);
+       /*
+        * Warning: Do not do the decrement at the same time as the call to
+        * flush_dcache_page() because it is a NULL macro on i386 and hence the
+        * decrement never happens so the loop never terminates.
+        */
+       do {
+               --nr_pages;
+               flush_dcache_page(pages[nr_pages]);
+       } while (nr_pages > 0);
+}
+
+/**
+ * ntfs_commit_pages_after_non_resident_write - commit the received data
+ * @pages:     array of destination pages
+ * @nr_pages:  number of pages in @pages
+ * @pos:       byte position in file at which the write begins
+ * @bytes:     number of bytes to be written
+ *
+ * See description of ntfs_commit_pages_after_write(), below.
+ */
+static inline int ntfs_commit_pages_after_non_resident_write(
+               struct page **pages, const unsigned nr_pages,
+               s64 pos, size_t bytes)
+{
+       s64 end, initialized_size;
+       struct inode *vi;
+       ntfs_inode *ni, *base_ni;
+       struct buffer_head *bh, *head;
+       ntfs_attr_search_ctx *ctx;
+       MFT_RECORD *m;
+       ATTR_RECORD *a;
+       unsigned long flags;
+       unsigned blocksize, u;
+       int err;
+
+       vi = pages[0]->mapping->host;
+       ni = NTFS_I(vi);
+       blocksize = vi->i_sb->s_blocksize;
+       end = pos + bytes;
+       u = 0;
+       do {
+               s64 bh_pos;
+               struct page *page;
+               bool partial;
+
+               page = pages[u];
+               bh_pos = (s64)page->index << PAGE_CACHE_SHIFT;
+               bh = head = page_buffers(page);
+               partial = false;
+               do {
+                       s64 bh_end;
+
+                       bh_end = bh_pos + blocksize;
+                       if (bh_end <= pos || bh_pos >= end) {
+                               if (!buffer_uptodate(bh))
+                                       partial = true;
+                       } else {
+                               set_buffer_uptodate(bh);
+                               mark_buffer_dirty(bh);
+                       }
+               } while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
+               /*
+                * If all buffers are now uptodate but the page is not, set the
+                * page uptodate.
+                */
+               if (!partial && !PageUptodate(page))
+                       SetPageUptodate(page);
+       } while (++u < nr_pages);
+       /*
+        * Finally, if we do not need to update initialized_size or i_size we
+        * are finished.
+        */
+       read_lock_irqsave(&ni->size_lock, flags);
+       initialized_size = ni->initialized_size;
+       read_unlock_irqrestore(&ni->size_lock, flags);
+       if (end <= initialized_size) {
+               ntfs_debug("Done.");
+               return 0;
+       }
+       /*
+        * Update initialized_size/i_size as appropriate, both in the inode and
+        * the mft record.
+        */
+       if (!NInoAttr(ni))
+               base_ni = ni;
+       else
+               base_ni = ni->ext.base_ntfs_ino;
+       /* Map, pin, and lock the mft record. */
+       m = map_mft_record(base_ni);
+       if (IS_ERR(m)) {
+               err = PTR_ERR(m);
+               m = NULL;
+               ctx = NULL;
+               goto err_out;
+       }
+       BUG_ON(!NInoNonResident(ni));
+       ctx = ntfs_attr_get_search_ctx(base_ni, m);
+       if (unlikely(!ctx)) {
+               err = -ENOMEM;
+               goto err_out;
+       }
+       err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+                       CASE_SENSITIVE, 0, NULL, 0, ctx);
+       if (unlikely(err)) {
+               if (err == -ENOENT)
+                       err = -EIO;
+               goto err_out;
+       }
+       a = ctx->attr;
+       BUG_ON(!a->non_resident);
+       write_lock_irqsave(&ni->size_lock, flags);
+       BUG_ON(end > ni->allocated_size);
+       ni->initialized_size = end;
+       a->data.non_resident.initialized_size = cpu_to_sle64(end);
+       if (end > i_size_read(vi)) {
+               i_size_write(vi, end);
+               a->data.non_resident.data_size =
+                               a->data.non_resident.initialized_size;
+       }
+       write_unlock_irqrestore(&ni->size_lock, flags);
+       /* Mark the mft record dirty, so it gets written back. */
+       flush_dcache_mft_record_page(ctx->ntfs_ino);
+       mark_mft_record_dirty(ctx->ntfs_ino);
+       ntfs_attr_put_search_ctx(ctx);
+       unmap_mft_record(base_ni);
+       ntfs_debug("Done.");
+       return 0;
+err_out:
+       if (ctx)
+               ntfs_attr_put_search_ctx(ctx);
+       if (m)
+               unmap_mft_record(base_ni);
+       ntfs_error(vi->i_sb, "Failed to update initialized_size/i_size (error "
+                       "code %i).", err);
+       if (err != -ENOMEM)
+               NVolSetErrors(ni->vol);
+       return err;
+}
+
+/**
+ * ntfs_commit_pages_after_write - commit the received data
+ * @pages:     array of destination pages
+ * @nr_pages:  number of pages in @pages
+ * @pos:       byte position in file at which the write begins
+ * @bytes:     number of bytes to be written
+ *
+ * This is called from ntfs_file_buffered_write() with i_mutex held on the inode
+ * (@pages[0]->mapping->host).  There are @nr_pages pages in @pages which are
+ * locked but not kmap()ped.  The source data has already been copied into the
+ * @page.  ntfs_prepare_pages_for_non_resident_write() has been called before
+ * the data was copied (for non-resident attributes only) and it returned
+ * success.
+ *
+ * Need to set uptodate and mark dirty all buffers within the boundary of the
+ * write.  If all buffers in a page are uptodate we set the page uptodate, too.
+ *
+ * Setting the buffers dirty ensures that they get written out later when
+ * ntfs_writepage() is invoked by the VM.
+ *
+ * Finally, we need to update i_size and initialized_size as appropriate both
+ * in the inode and the mft record.
+ *
+ * This is modelled after fs/buffer.c::generic_commit_write(), which marks
+ * buffers uptodate and dirty, sets the page uptodate if all buffers in the
+ * page are uptodate, and updates i_size if the end of io is beyond i_size.  In
+ * that case, it also marks the inode dirty.
+ *
+ * If things have gone as outlined in
+ * ntfs_prepare_pages_for_non_resident_write(), we do not need to do any page
+ * content modifications here for non-resident attributes.  For resident
+ * attributes we need to do the uptodate bringing here which we combine with
+ * the copying into the mft record which means we save one atomic kmap.
+ *
+ * Return 0 on success or -errno on error.
+ */
+static int ntfs_commit_pages_after_write(struct page **pages,
+               const unsigned nr_pages, s64 pos, size_t bytes)
+{
+       s64 end, initialized_size;
+       loff_t i_size;
+       struct inode *vi;
+       ntfs_inode *ni, *base_ni;
+       struct page *page;
+       ntfs_attr_search_ctx *ctx;
+       MFT_RECORD *m;
+       ATTR_RECORD *a;
+       char *kattr, *kaddr;
+       unsigned long flags;
+       u32 attr_len;
+       int err;
+
+       BUG_ON(!nr_pages);
+       BUG_ON(!pages);
+       page = pages[0];
+       BUG_ON(!page);
+       vi = page->mapping->host;
+       ni = NTFS_I(vi);
+       ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
+                       "index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
+                       vi->i_ino, ni->type, page->index, nr_pages,
+                       (long long)pos, bytes);
+       if (NInoNonResident(ni))
+               return ntfs_commit_pages_after_non_resident_write(pages,
+                               nr_pages, pos, bytes);
+       BUG_ON(nr_pages > 1);
+       /*
+        * Attribute is resident, implying it is not compressed, encrypted, or
+        * sparse.
+        */
+       if (!NInoAttr(ni))
+               base_ni = ni;
+       else
+               base_ni = ni->ext.base_ntfs_ino;
+       BUG_ON(NInoNonResident(ni));
+       /* Map, pin, and lock the mft record. */
+       m = map_mft_record(base_ni);
+       if (IS_ERR(m)) {
+               err = PTR_ERR(m);
+               m = NULL;
+               ctx = NULL;
+               goto err_out;
+       }
+       ctx = ntfs_attr_get_search_ctx(base_ni, m);
+       if (unlikely(!ctx)) {
+               err = -ENOMEM;
+               goto err_out;
+       }
+       err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+                       CASE_SENSITIVE, 0, NULL, 0, ctx);
+       if (unlikely(err)) {
+               if (err == -ENOENT)
+                       err = -EIO;
+               goto err_out;
+       }
+       a = ctx->attr;
+       BUG_ON(a->non_resident);
+       /* The total length of the attribute value. */
+       attr_len = le32_to_cpu(a->data.resident.value_length);
+       i_size = i_size_read(vi);
+       BUG_ON(attr_len != i_size);
+       BUG_ON(pos > attr_len);
+       end = pos + bytes;
+       BUG_ON(end > le32_to_cpu(a->length) -
+                       le16_to_cpu(a->data.resident.value_offset));
+       kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
+       kaddr = kmap_atomic(page, KM_USER0);
+       /* Copy the received data from the page to the mft record. */
+       memcpy(kattr + pos, kaddr + pos, bytes);
+       /* Update the attribute length if necessary. */
+       if (end > attr_len) {
+               attr_len = end;
+               a->data.resident.value_length = cpu_to_le32(attr_len);
+       }
+       /*
+        * If the page is not uptodate, bring the out of bounds area(s)
+        * uptodate by copying data from the mft record to the page.
+        */
+       if (!PageUptodate(page)) {
+               if (pos > 0)
+                       memcpy(kaddr, kattr, pos);
+               if (end < attr_len)
+                       memcpy(kaddr + end, kattr + end, attr_len - end);
+               /* Zero the region outside the end of the attribute value. */
+               memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
+               flush_dcache_page(page);
+               SetPageUptodate(page);
+       }
+       kunmap_atomic(kaddr, KM_USER0);
+       /* Update initialized_size/i_size if necessary. */
+       read_lock_irqsave(&ni->size_lock, flags);
+       initialized_size = ni->initialized_size;
+       BUG_ON(end > ni->allocated_size);
+       read_unlock_irqrestore(&ni->size_lock, flags);
+       BUG_ON(initialized_size != i_size);
+       if (end > initialized_size) {
+               write_lock_irqsave(&ni->size_lock, flags);
+               ni->initialized_size = end;
+               i_size_write(vi, end);
+               write_unlock_irqrestore(&ni->size_lock, flags);
+       }
+       /* Mark the mft record dirty, so it gets written back. */
+       flush_dcache_mft_record_page(ctx->ntfs_ino);
+       mark_mft_record_dirty(ctx->ntfs_ino);
+       ntfs_attr_put_search_ctx(ctx);
+       unmap_mft_record(base_ni);
+       ntfs_debug("Done.");
+       return 0;
+err_out:
+       if (err == -ENOMEM) {
+               ntfs_warning(vi->i_sb, "Error allocating memory required to "
+                               "commit the write.");
+               if (PageUptodate(page)) {
+                       ntfs_warning(vi->i_sb, "Page is uptodate, setting "
+                                       "dirty so the write will be retried "
+                                       "later on by the VM.");
+                       /*
+                        * Put the page on mapping->dirty_pages, but leave its
+                        * buffers' dirty state as-is.
+                        */
+                       __set_page_dirty_nobuffers(page);
+                       err = 0;
+               } else
+                       ntfs_error(vi->i_sb, "Page is not uptodate.  Written "
+                                       "data has been lost.");
+       } else {
+               ntfs_error(vi->i_sb, "Resident attribute commit write failed "
+                               "with error %i.", err);
+               NVolSetErrors(ni->vol);
+       }
+       if (ctx)
+               ntfs_attr_put_search_ctx(ctx);
+       if (m)
+               unmap_mft_record(base_ni);
+       return err;
+}
+
+/**
+ * ntfs_file_buffered_write -
+ *
+ * Locking: The vfs is holding ->i_mutex on the inode.
+ */
+static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
+               const struct iovec *iov, unsigned long nr_segs,
+               loff_t pos, loff_t *ppos, size_t count)
+{
+       struct file *file = iocb->ki_filp;
+       struct address_space *mapping = file->f_mapping;
+       struct inode *vi = mapping->host;
+       ntfs_inode *ni = NTFS_I(vi);
+       ntfs_volume *vol = ni->vol;
+       struct page *pages[NTFS_MAX_PAGES_PER_CLUSTER];
+       struct page *cached_page = NULL;
+       char __user *buf = NULL;
+       s64 end, ll;
+       VCN last_vcn;
+       LCN lcn;
+       unsigned long flags;
+       size_t bytes, iov_ofs = 0;      /* Offset in the current iovec. */
+       ssize_t status, written;
+       unsigned nr_pages;
+       int err;
+       struct pagevec lru_pvec;
+
+       ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
+                       "pos 0x%llx, count 0x%lx.",
+                       vi->i_ino, (unsigned)le32_to_cpu(ni->type),
+                       (unsigned long long)pos, (unsigned long)count);
+       if (unlikely(!count))
+               return 0;
+       BUG_ON(NInoMstProtected(ni));
+       /*
+        * If the attribute is not an index root and it is encrypted or
+        * compressed, we cannot write to it yet.  Note we need to check for
+        * AT_INDEX_ALLOCATION since this is the type of both directory and
+        * index inodes.
+        */
+       if (ni->type != AT_INDEX_ALLOCATION) {
+               /* If file is encrypted, deny access, just like NT4. */
+               if (NInoEncrypted(ni)) {
+                       /*
+                        * Reminder for later: Encrypted files are _always_
+                        * non-resident so that the content can always be
+                        * encrypted.
+                        */
+                       ntfs_debug("Denying write access to encrypted file.");
+                       return -EACCES;
+               }
+               if (NInoCompressed(ni)) {
+                       /* Only unnamed $DATA attribute can be compressed. */
+                       BUG_ON(ni->type != AT_DATA);
+                       BUG_ON(ni->name_len);
+                       /*
+                        * Reminder for later: If resident, the data is not
+                        * actually compressed.  Only on the switch to non-
+                        * resident does compression kick in.  This is in
+                        * contrast to encrypted files (see above).
+                        */
+                       ntfs_error(vi->i_sb, "Writing to compressed files is "
+                                       "not implemented yet.  Sorry.");
+                       return -EOPNOTSUPP;
+               }
+       }
+       /*
+        * If a previous ntfs_truncate() failed, repeat it and abort if it
+        * fails again.
+        */
+       if (unlikely(NInoTruncateFailed(ni))) {
+               down_write(&vi->i_alloc_sem);
+               err = ntfs_truncate(vi);
+               up_write(&vi->i_alloc_sem);
+               if (err || NInoTruncateFailed(ni)) {
+                       if (!err)
+                               err = -EIO;
+                       ntfs_error(vol->sb, "Cannot perform write to inode "
+                                       "0x%lx, attribute type 0x%x, because "
+                                       "ntfs_truncate() failed (error code "
+                                       "%i).", vi->i_ino,
+                                       (unsigned)le32_to_cpu(ni->type), err);
+                       return err;
+               }
+       }
+       /* The first byte after the write. */
+       end = pos + count;
+       /*
+        * If the write goes beyond the allocated size, extend the allocation
+        * to cover the whole of the write, rounded up to the nearest cluster.
+        */
+       read_lock_irqsave(&ni->size_lock, flags);
+       ll = ni->allocated_size;
+       read_unlock_irqrestore(&ni->size_lock, flags);
+       if (end > ll) {
+               /* Extend the allocation without changing the data size. */
+               ll = ntfs_attr_extend_allocation(ni, end, -1, pos);
+               if (likely(ll >= 0)) {
+                       BUG_ON(pos >= ll);
+                       /* If the extension was partial truncate the write. */
+                       if (end > ll) {
+                               ntfs_debug("Truncating write to inode 0x%lx, "
+                                               "attribute type 0x%x, because "
+                                               "the allocation was only "
+                                               "partially extended.",
+                                               vi->i_ino, (unsigned)
+                                               le32_to_cpu(ni->type));
+                               end = ll;
+                               count = ll - pos;
+                       }
+               } else {
+                       err = ll;
+                       read_lock_irqsave(&ni->size_lock, flags);
+                       ll = ni->allocated_size;
+                       read_unlock_irqrestore(&ni->size_lock, flags);
+                       /* Perform a partial write if possible or fail. */
+                       if (pos < ll) {
+                               ntfs_debug("Truncating write to inode 0x%lx, "
+                                               "attribute type 0x%x, because "
+                                               "extending the allocation "
+                                               "failed (error code %i).",
+                                               vi->i_ino, (unsigned)
+                                               le32_to_cpu(ni->type), err);
+                               end = ll;
+                               count = ll - pos;
+                       } else {
+                               ntfs_error(vol->sb, "Cannot perform write to "
+                                               "inode 0x%lx, attribute type "
+                                               "0x%x, because extending the "
+                                               "allocation failed (error "
+                                               "code %i).", vi->i_ino,
+                                               (unsigned)
+                                               le32_to_cpu(ni->type), err);
+                               return err;
+                       }
+               }
+       }
+       pagevec_init(&lru_pvec, 0);
+       written = 0;
+       /*
+        * If the write starts beyond the initialized size, extend it up to the
+        * beginning of the write and initialize all non-sparse space between
+        * the old initialized size and the new one.  This automatically also
+        * increments the vfs inode->i_size to keep it above or equal to the
+        * initialized_size.
+        */
+       read_lock_irqsave(&ni->size_lock, flags);
+       ll = ni->initialized_size;
+       read_unlock_irqrestore(&ni->size_lock, flags);
+       if (pos > ll) {
+               err = ntfs_attr_extend_initialized(ni, pos, &cached_page,
+                               &lru_pvec);
+               if (err < 0) {
+                       ntfs_error(vol->sb, "Cannot perform write to inode "
+                                       "0x%lx, attribute type 0x%x, because "
+                                       "extending the initialized size "
+                                       "failed (error code %i).", vi->i_ino,
+                                       (unsigned)le32_to_cpu(ni->type), err);
+                       status = err;
+                       goto err_out;
+               }
+       }
+       /*
+        * Determine the number of pages per cluster for non-resident
+        * attributes.
+        */
+       nr_pages = 1;
+       if (vol->cluster_size > PAGE_CACHE_SIZE && NInoNonResident(ni))
+               nr_pages = vol->cluster_size >> PAGE_CACHE_SHIFT;
+       /* Finally, perform the actual write. */
+       last_vcn = -1;
+       if (likely(nr_segs == 1))
+               buf = iov->iov_base;
+       do {
+               VCN vcn;
+               pgoff_t idx, start_idx;
+               unsigned ofs, do_pages, u;
+               size_t copied;
+
+               start_idx = idx = pos >> PAGE_CACHE_SHIFT;
+               ofs = pos & ~PAGE_CACHE_MASK;
+               bytes = PAGE_CACHE_SIZE - ofs;
+               do_pages = 1;
+               if (nr_pages > 1) {
+                       vcn = pos >> vol->cluster_size_bits;
+                       if (vcn != last_vcn) {
+                               last_vcn = vcn;
+                               /*
+                                * Get the lcn of the vcn the write is in.  If
+                                * it is a hole, need to lock down all pages in
+                                * the cluster.
+                                */
+                               down_read(&ni->runlist.lock);
+                               lcn = ntfs_attr_vcn_to_lcn_nolock(ni, pos >>
+                                               vol->cluster_size_bits, false);
+                               up_read(&ni->runlist.lock);
+                               if (unlikely(lcn < LCN_HOLE)) {
+                                       status = -EIO;
+                                       if (lcn == LCN_ENOMEM)
+                                               status = -ENOMEM;
+                                       else
+                                               ntfs_error(vol->sb, "Cannot "
+                                                       "perform write to "
+                                                       "inode 0x%lx, "
+                                                       "attribute type 0x%x, "
+                                                       "because the attribute "
+                                                       "is corrupt.",
+                                                       vi->i_ino, (unsigned)
+                                                       le32_to_cpu(ni->type));
+                                       break;
+                               }
+                               if (lcn == LCN_HOLE) {
+                                       start_idx = (pos & ~(s64)
+                                                       vol->cluster_size_mask)
+                                                       >> PAGE_CACHE_SHIFT;
+                                       bytes = vol->cluster_size - (pos &
+                                                       vol->cluster_size_mask);
+                                       do_pages = nr_pages;
+                               }
+                       }
+               }
+               if (bytes > count)
+                       bytes = count;
+               /*
+                * Bring in the user page(s) that we will copy from _first_.
+                * Otherwise there is a nasty deadlock on copying from the same
+                * page(s) as we are writing to, without it/them being marked
+                * up-to-date.  Note, at present there is nothing to stop the
+                * pages being swapped out between us bringing them into memory
+                * and doing the actual copying.
+                */
+               if (likely(nr_segs == 1))
+                       ntfs_fault_in_pages_readable(buf, bytes);
+               else
+                       ntfs_fault_in_pages_readable_iovec(iov, iov_ofs, bytes);
+               /* Get and lock @do_pages starting at index @start_idx. */
+               status = __ntfs_grab_cache_pages(mapping, start_idx, do_pages,
+                               pages, &cached_page, &lru_pvec);
+               if (unlikely(status))
+                       break;
+               /*
+                * For non-resident attributes, we need to fill any holes with
+                * actual clusters and ensure all bufferes are mapped.  We also
+                * need to bring uptodate any buffers that are only partially
+                * being written to.
+                */
+               if (NInoNonResident(ni)) {
+                       status = ntfs_prepare_pages_for_non_resident_write(
+                                       pages, do_pages, pos, bytes);
+                       if (unlikely(status)) {
+                               loff_t i_size;
+
+                               do {
+                                       unlock_page(pages[--do_pages]);
+                                       page_cache_release(pages[do_pages]);
+                               } while (do_pages);
+                               /*
+                                * The write preparation may have instantiated
+                                * allocated space outside i_size.  Trim this
+                                * off again.  We can ignore any errors in this
+                                * case as we will just be waisting a bit of
+                                * allocated space, which is not a disaster.
+                                */
+                               i_size = i_size_read(vi);
+                               if (pos + bytes > i_size)
+                                       vmtruncate(vi, i_size);
+                               break;
+                       }
+               }
+               u = (pos >> PAGE_CACHE_SHIFT) - pages[0]->index;
+               if (likely(nr_segs == 1)) {
+                       copied = ntfs_copy_from_user(pages + u, do_pages - u,
+                                       ofs, buf, bytes);
+                       buf += copied;
+               } else
+                       copied = ntfs_copy_from_user_iovec(pages + u,
+                                       do_pages - u, ofs, &iov, &iov_ofs,
+                                       bytes);
+               ntfs_flush_dcache_pages(pages + u, do_pages - u);
+               status = ntfs_commit_pages_after_write(pages, do_pages, pos,
+                               bytes);
+               if (likely(!status)) {
+                       written += copied;
+                       count -= copied;
+                       pos += copied;
+                       if (unlikely(copied != bytes))
+                               status = -EFAULT;
+               }
+               do {
+                       unlock_page(pages[--do_pages]);
+                       mark_page_accessed(pages[do_pages]);
+                       page_cache_release(pages[do_pages]);
+               } while (do_pages);
+               if (unlikely(status))
+                       break;
+               balance_dirty_pages_ratelimited(mapping);
+               cond_resched();
+       } while (count);
+err_out:
+       *ppos = pos;
+       if (cached_page)
+               page_cache_release(cached_page);
+       pagevec_lru_add_file(&lru_pvec);
+       ntfs_debug("Done.  Returning %s (written 0x%lx, status %li).",
+                       written ? "written" : "status", (unsigned long)written,
+                       (long)status);
+       return written ? written : status;
+}
+
+/**
+ * ntfs_file_aio_write_nolock -
+ */
+static ssize_t ntfs_file_aio_write_nolock(struct kiocb *iocb,
+               const struct iovec *iov, unsigned long nr_segs, loff_t *ppos)
+{
+       struct file *file = iocb->ki_filp;
+       struct address_space *mapping = file->f_mapping;
+       struct inode *inode = mapping->host;
+       loff_t pos;
+       size_t count;           /* after file limit checks */
+       ssize_t written, err;
+
+       count = 0;
+       err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
+       if (err)
+               return err;
+       pos = *ppos;
+       vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+       /* We can write back this queue in page reclaim. */
+       current->backing_dev_info = mapping->backing_dev_info;
+       written = 0;
+       err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
+       if (err)
+               goto out;
+       if (!count)
+               goto out;
+       err = file_remove_suid(file);
+       if (err)
+               goto out;
+       file_update_time(file);
+       written = ntfs_file_buffered_write(iocb, iov, nr_segs, pos, ppos,
+                       count);
+out:
+       current->backing_dev_info = NULL;
+       return written ? written : err;
+}
+
+/**
+ * ntfs_file_aio_write -
+ */
+static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
+               unsigned long nr_segs, loff_t pos)
+{
+       struct file *file = iocb->ki_filp;
+       struct address_space *mapping = file->f_mapping;
+       struct inode *inode = mapping->host;
+       ssize_t ret;
+
+       BUG_ON(iocb->ki_pos != pos);
+
+       mutex_lock(&inode->i_mutex);
+       ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos);
+       mutex_unlock(&inode->i_mutex);
+       if (ret > 0) {
+               int err = generic_write_sync(file, pos, ret);
+               if (err < 0)
+                       ret = err;
+       }
+       return ret;
+}
+
+/**
  * ntfs_file_fsync - sync a file to disk
  * @filp:      file to be synced
  * @dentry:    dentry describing the file to sync
@@ -77,7 +2167,7 @@ static int ntfs_file_open(struct inode *vi, struct file *filp)
  * Note: In the past @filp could be NULL so we ignore it as we don't need it
  * anyway.
  *
- * Locking: Caller must hold i_sem on the inode.
+ * Locking: Caller must hold i_mutex on the inode.
  *
  * TODO: We should probably also write all attribute/index inodes associated
  * with this inode but since we have no simple way of getting to them we ignore
@@ -112,49 +2202,47 @@ static int ntfs_file_fsync(struct file *filp, struct dentry *dentry,
 
 #endif /* NTFS_RW */
 
-struct file_operations ntfs_file_ops = {
-       .llseek         = generic_file_llseek,    /* Seek inside file. */
-       .read           = generic_file_read,      /* Read from file. */
-       .aio_read       = generic_file_aio_read,  /* Async read from file. */
-       .readv          = generic_file_readv,     /* Read from file. */
+const struct file_operations ntfs_file_ops = {
+       .llseek         = generic_file_llseek,   /* Seek inside file. */
+       .read           = do_sync_read,          /* Read from file. */
+       .aio_read       = generic_file_aio_read, /* Async read from file. */
 #ifdef NTFS_RW
-       .write          = generic_file_write,     /* Write to file. */
-       .aio_write      = generic_file_aio_write, /* Async write to file. */
-       .writev         = generic_file_writev,    /* Write to file. */
-       /*.release      = ,*/                     /* Last file is closed.  See
-                                                    fs/ext2/file.c::
-                                                    ext2_release_file() for
-                                                    how to use this to discard
-                                                    preallocated space for
-                                                    write opened files. */
-       .fsync          = ntfs_file_fsync,        /* Sync a file to disk. */
-       /*.aio_fsync    = ,*/                     /* Sync all outstanding async
-                                                    i/o operations on a
-                                                    kiocb. */
+       .write          = do_sync_write,         /* Write to file. */
+       .aio_write      = ntfs_file_aio_write,   /* Async write to file. */
+       /*.release      = ,*/                    /* Last file is closed.  See
+                                                   fs/ext2/file.c::
+                                                   ext2_release_file() for
+                                                   how to use this to discard
+                                                   preallocated space for
+                                                   write opened files. */
+       .fsync          = ntfs_file_fsync,       /* Sync a file to disk. */
+       /*.aio_fsync    = ,*/                    /* Sync all outstanding async
+                                                   i/o operations on a
+                                                   kiocb. */
 #endif /* NTFS_RW */
-       /*.ioctl        = ,*/                     /* Perform function on the
-                                                    mounted filesystem. */
-       .mmap           = generic_file_mmap,      /* Mmap file. */
-       .open           = ntfs_file_open,         /* Open file. */
-       .sendfile       = generic_file_sendfile,  /* Zero-copy data send with
-                                                    the data source being on
-                                                    the ntfs partition.  We
-                                                    do not need to care about
-                                                    the data destination. */
-       /*.sendpage     = ,*/                     /* Zero-copy data send with
-                                                    the data destination being
-                                                    on the ntfs partition.  We
-                                                    do not need to care about
-                                                    the data source. */
+       /*.ioctl        = ,*/                    /* Perform function on the
+                                                   mounted filesystem. */
+       .mmap           = generic_file_mmap,     /* Mmap file. */
+       .open           = ntfs_file_open,        /* Open file. */
+       .splice_read    = generic_file_splice_read /* Zero-copy data send with
+                                                   the data source being on
+                                                   the ntfs partition.  We do
+                                                   not need to care about the
+                                                   data destination. */
+       /*.sendpage     = ,*/                    /* Zero-copy data send with
+                                                   the data destination being
+                                                   on the ntfs partition.  We
+                                                   do not need to care about
+                                                   the data source. */
 };
 
-struct inode_operations ntfs_file_inode_ops = {
+const struct inode_operations ntfs_file_inode_ops = {
 #ifdef NTFS_RW
        .truncate       = ntfs_truncate_vfs,
        .setattr        = ntfs_setattr,
 #endif /* NTFS_RW */
 };
 
-struct file_operations ntfs_empty_file_ops = {};
+const struct file_operations ntfs_empty_file_ops = {};
 
-struct inode_operations ntfs_empty_inode_ops = {};
+const struct inode_operations ntfs_empty_inode_ops = {};