NTFS: Remove address space operations ->prepare_write and ->commit_write in
Anton Altaparmakov [Tue, 11 Oct 2005 13:59:40 +0000 (14:59 +0100)]
      preparation for the big rewrite of write(2) support in ntfs.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

fs/ntfs/aops.c

index 5e80c07..8f23c60 100644 (file)
@@ -1542,830 +1542,6 @@ err_out:
        return err;
 }
 
-/**
- * ntfs_prepare_nonresident_write -
- *
- */
-static int ntfs_prepare_nonresident_write(struct page *page,
-               unsigned from, unsigned to)
-{
-       VCN vcn;
-       LCN lcn;
-       s64 initialized_size;
-       loff_t i_size;
-       sector_t block, ablock, iblock;
-       struct inode *vi;
-       ntfs_inode *ni;
-       ntfs_volume *vol;
-       runlist_element *rl;
-       struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
-       unsigned long flags;
-       unsigned int vcn_ofs, block_start, block_end, blocksize;
-       int err;
-       BOOL is_retry;
-       unsigned char blocksize_bits;
-
-       vi = page->mapping->host;
-       ni = NTFS_I(vi);
-       vol = ni->vol;
-
-       ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
-                       "0x%lx, from = %u, to = %u.", ni->mft_no, ni->type,
-                       page->index, from, to);
-
-       BUG_ON(!NInoNonResident(ni));
-
-       blocksize_bits = vi->i_blkbits;
-       blocksize = 1 << blocksize_bits;
-
-       /*
-        * 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);
-       bh = head = page_buffers(page);
-       if (unlikely(!bh))
-               return -ENOMEM;
-
-       /* The first block in the page. */
-       block = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
-
-       read_lock_irqsave(&ni->size_lock, flags);
-       /*
-        * The first out of bounds block for the allocated size.  No need to
-        * round up as allocated_size is in multiples of cluster size and the
-        * minimum cluster size is 512 bytes, which is equal to the smallest
-        * blocksize.
-        */
-       ablock = ni->allocated_size >> blocksize_bits;
-       i_size = i_size_read(vi);
-       initialized_size = ni->initialized_size;
-       read_unlock_irqrestore(&ni->size_lock, flags);
-
-       /* The last (fully or partially) initialized block. */
-       iblock = initialized_size >> blocksize_bits;
-
-       /* Loop through all the buffers in the page. */
-       block_start = 0;
-       rl = NULL;
-       err = 0;
-       do {
-               block_end = block_start + blocksize;
-               /*
-                * If buffer @bh is outside the write, just mark it uptodate
-                * if the page is uptodate and continue with the next buffer.
-                */
-               if (block_end <= from || block_start >= to) {
-                       if (PageUptodate(page)) {
-                               if (!buffer_uptodate(bh))
-                                       set_buffer_uptodate(bh);
-                       }
-                       continue;
-               }
-               /*
-                * @bh is at least partially being written to.
-                * Make sure it is not marked as new.
-                */
-               //if (buffer_new(bh))
-               //      clear_buffer_new(bh);
-
-               if (block >= ablock) {
-                       // TODO: block is above allocated_size, need to
-                       // allocate it. Best done in one go to accommodate not
-                       // only block but all above blocks up to and including:
-                       // ((page->index << PAGE_CACHE_SHIFT) + to + blocksize
-                       // - 1) >> blobksize_bits. Obviously will need to round
-                       // up to next cluster boundary, too. This should be
-                       // done with a helper function, so it can be reused.
-                       ntfs_error(vol->sb, "Writing beyond allocated size "
-                                       "is not supported yet. Sorry.");
-                       err = -EOPNOTSUPP;
-                       goto err_out;
-                       // Need to update ablock.
-                       // Need to set_buffer_new() on all block bhs that are
-                       // newly allocated.
-               }
-               /*
-                * Now we have enough allocated size to fulfill the whole
-                * request, i.e. block < ablock is true.
-                */
-               if (unlikely((block >= iblock) &&
-                               (initialized_size < i_size))) {
-                       /*
-                        * If this page is fully outside initialized size, zero
-                        * out all pages between the current initialized size
-                        * and the current page. Just use ntfs_readpage() to do
-                        * the zeroing transparently.
-                        */
-                       if (block > iblock) {
-                               // TODO:
-                               // For each page do:
-                               // - read_cache_page()
-                               // Again for each page do:
-                               // - wait_on_page_locked()
-                               // - Check (PageUptodate(page) &&
-                               //                      !PageError(page))
-                               // Update initialized size in the attribute and
-                               // in the inode.
-                               // Again, for each page do:
-                               //      __set_page_dirty_buffers();
-                               // page_cache_release()
-                               // We don't need to wait on the writes.
-                               // Update iblock.
-                       }
-                       /*
-                        * The current page straddles initialized size. Zero
-                        * all non-uptodate buffers and set them uptodate (and
-                        * dirty?). Note, there aren't any non-uptodate buffers
-                        * if the page is uptodate.
-                        * FIXME: For an uptodate page, the buffers may need to
-                        * be written out because they were not initialized on
-                        * disk before.
-                        */
-                       if (!PageUptodate(page)) {
-                               // TODO:
-                               // Zero any non-uptodate buffers up to i_size.
-                               // Set them uptodate and dirty.
-                       }
-                       // TODO:
-                       // Update initialized size in the attribute and in the
-                       // inode (up to i_size).
-                       // Update iblock.
-                       // FIXME: This is inefficient. Try to batch the two
-                       // size changes to happen in one go.
-                       ntfs_error(vol->sb, "Writing beyond initialized size "
-                                       "is not supported yet. Sorry.");
-                       err = -EOPNOTSUPP;
-                       goto err_out;
-                       // Do NOT set_buffer_new() BUT DO clear buffer range
-                       // outside write request range.
-                       // set_buffer_uptodate() on complete buffers as well as
-                       // set_buffer_dirty().
-               }
-
-               /* Need to map unmapped buffers. */
-               if (!buffer_mapped(bh)) {
-                       /* Unmapped buffer. Need to map it. */
-                       bh->b_bdev = vol->sb->s_bdev;
-
-                       /* Convert block into corresponding vcn and offset. */
-                       vcn = (VCN)block << blocksize_bits >>
-                                       vol->cluster_size_bits;
-                       vcn_ofs = ((VCN)block << blocksize_bits) &
-                                       vol->cluster_size_mask;
-
-                       is_retry = FALSE;
-                       if (!rl) {
-lock_retry_remap:
-                               down_read(&ni->runlist.lock);
-                               rl = ni->runlist.rl;
-                       }
-                       if (likely(rl != NULL)) {
-                               /* Seek to element containing target vcn. */
-                               while (rl->length && rl[1].vcn <= vcn)
-                                       rl++;
-                               lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
-                       } else
-                               lcn = LCN_RL_NOT_MAPPED;
-                       if (unlikely(lcn < 0)) {
-                               /*
-                                * We extended the attribute allocation above.
-                                * If we hit an ENOENT here it means that the
-                                * allocation was insufficient which is a bug.
-                                */
-                               BUG_ON(lcn == LCN_ENOENT);
-
-                               /* It is a hole, need to instantiate it. */
-                               if (lcn == LCN_HOLE) {
-                                       // TODO: Instantiate the hole.
-                                       // clear_buffer_new(bh);
-                                       // unmap_underlying_metadata(bh->b_bdev,
-                                       //              bh->b_blocknr);
-                                       // For non-uptodate buffers, need to
-                                       // zero out the region outside the
-                                       // request in this bh or all bhs,
-                                       // depending on what we implemented
-                                       // above.
-                                       // Need to flush_dcache_page().
-                                       // Or could use set_buffer_new()
-                                       // instead?
-                                       ntfs_error(vol->sb, "Writing into "
-                                                       "sparse regions is "
-                                                       "not supported yet. "
-                                                       "Sorry.");
-                                       err = -EOPNOTSUPP;
-                                       if (!rl)
-                                               up_read(&ni->runlist.lock);
-                                       goto err_out;
-                               } else if (!is_retry &&
-                                               lcn == LCN_RL_NOT_MAPPED) {
-                                       is_retry = TRUE;
-                                       /*
-                                        * Attempt to map runlist, dropping
-                                        * lock for the duration.
-                                        */
-                                       up_read(&ni->runlist.lock);
-                                       err = ntfs_map_runlist(ni, vcn);
-                                       if (likely(!err))
-                                               goto lock_retry_remap;
-                                       rl = NULL;
-                               } else if (!rl)
-                                       up_read(&ni->runlist.lock);
-                               /*
-                                * Failed to map the buffer, even after
-                                * retrying.
-                                */
-                               if (!err)
-                                       err = -EIO;
-                               bh->b_blocknr = -1;
-                               ntfs_error(vol->sb, "Failed to write to inode "
-                                               "0x%lx, attribute type 0x%x, "
-                                               "vcn 0x%llx, offset 0x%x "
-                                               "because its location on disk "
-                                               "could not be determined%s "
-                                               "(error code %i).",
-                                               ni->mft_no, ni->type,
-                                               (unsigned long long)vcn,
-                                               vcn_ofs, is_retry ? " even "
-                                               "after retrying" : "", err);
-                               goto err_out;
-                       }
-                       /* We now have a successful remap, i.e. lcn >= 0. */
-
-                       /* Setup buffer head to correct block. */
-                       bh->b_blocknr = ((lcn << vol->cluster_size_bits)
-                                       + vcn_ofs) >> blocksize_bits;
-                       set_buffer_mapped(bh);
-
-                       // FIXME: Something analogous to this is needed for
-                       // each newly allocated block, i.e. BH_New.
-                       // FIXME: Might need to take this out of the
-                       // if (!buffer_mapped(bh)) {}, depending on how we
-                       // implement things during the allocated_size and
-                       // initialized_size extension code above.
-                       if (buffer_new(bh)) {
-                               clear_buffer_new(bh);
-                               unmap_underlying_metadata(bh->b_bdev,
-                                               bh->b_blocknr);
-                               if (PageUptodate(page)) {
-                                       set_buffer_uptodate(bh);
-                                       continue;
-                               }
-                               /*
-                                * Page is _not_ uptodate, zero surrounding
-                                * region. NOTE: This is how we decide if to
-                                * zero or not!
-                                */
-                               if (block_end > to || block_start < from) {
-                                       void *kaddr;
-
-                                       kaddr = kmap_atomic(page, KM_USER0);
-                                       if (block_end > to)
-                                               memset(kaddr + to, 0,
-                                                               block_end - to);
-                                       if (block_start < from)
-                                               memset(kaddr + block_start, 0,
-                                                               from -
-                                                               block_start);
-                                       flush_dcache_page(page);
-                                       kunmap_atomic(kaddr, KM_USER0);
-                               }
-                               continue;
-                       }
-               }
-               /* @bh is mapped, set it uptodate if the page is uptodate. */
-               if (PageUptodate(page)) {
-                       if (!buffer_uptodate(bh))
-                               set_buffer_uptodate(bh);
-                       continue;
-               }
-               /*
-                * The page is not uptodate. The buffer is mapped. If it is not
-                * uptodate, and it is only partially being written to, we need
-                * to read the buffer in before the write, i.e. right now.
-                */
-               if (!buffer_uptodate(bh) &&
-                               (block_start < from || block_end > to)) {
-                       ll_rw_block(READ, 1, &bh);
-                       *wait_bh++ = bh;
-               }
-       } while (block++, block_start = block_end,
-                       (bh = bh->b_this_page) != head);
-
-       /* Release the lock if we took it. */
-       if (rl) {
-               up_read(&ni->runlist.lock);
-               rl = NULL;
-       }
-
-       /* If we issued read requests, let them complete. */
-       while (wait_bh > wait) {
-               wait_on_buffer(*--wait_bh);
-               if (!buffer_uptodate(*wait_bh))
-                       return -EIO;
-       }
-
-       ntfs_debug("Done.");
-       return 0;
-err_out:
-       /*
-        * Zero out any newly allocated blocks to avoid exposing stale data.
-        * If BH_New is set, we know that the block was newly allocated in the
-        * above loop.
-        * FIXME: What about initialized_size increments? Have we done all the
-        * required zeroing above? If not this error handling is broken, and
-        * in particular the if (block_end <= from) check is completely bogus.
-        */
-       bh = head;
-       block_start = 0;
-       is_retry = FALSE;
-       do {
-               block_end = block_start + blocksize;
-               if (block_end <= from)
-                       continue;
-               if (block_start >= to)
-                       break;
-               if (buffer_new(bh)) {
-                       void *kaddr;
-
-                       clear_buffer_new(bh);
-                       kaddr = kmap_atomic(page, KM_USER0);
-                       memset(kaddr + block_start, 0, bh->b_size);
-                       kunmap_atomic(kaddr, KM_USER0);
-                       set_buffer_uptodate(bh);
-                       mark_buffer_dirty(bh);
-                       is_retry = TRUE;
-               }
-       } while (block_start = block_end, (bh = bh->b_this_page) != head);
-       if (is_retry)
-               flush_dcache_page(page);
-       if (rl)
-               up_read(&ni->runlist.lock);
-       return err;
-}
-
-/**
- * ntfs_prepare_write - prepare a page for receiving data
- *
- * This is called from generic_file_write() with i_sem held on the inode
- * (@page->mapping->host).  The @page is locked but not kmap()ped.  The source
- * data has not yet been copied into the @page.
- *
- * Need to extend the attribute/fill in holes if necessary, create blocks and
- * make partially overwritten blocks uptodate,
- *
- * i_size is not to be modified yet.
- *
- * Return 0 on success or -errno on error.
- *
- * Should be using block_prepare_write() [support for sparse files] or
- * cont_prepare_write() [no support for sparse files].  Cannot do that due to
- * ntfs specifics but can look at them for implementation guidance.
- *
- * Note: In the range, @from is inclusive and @to is exclusive, i.e. @from is
- * the first byte in the page that will be written to and @to is the first byte
- * after the last byte that will be written to.
- */
-static int ntfs_prepare_write(struct file *file, struct page *page,
-               unsigned from, unsigned to)
-{
-       s64 new_size;
-       loff_t i_size;
-       struct inode *vi = page->mapping->host;
-       ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi);
-       ntfs_volume *vol = ni->vol;
-       ntfs_attr_search_ctx *ctx = NULL;
-       MFT_RECORD *m = NULL;
-       ATTR_RECORD *a;
-       u8 *kaddr;
-       u32 attr_len;
-       int err;
-
-       ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
-                       "0x%lx, from = %u, to = %u.", vi->i_ino, ni->type,
-                       page->index, from, to);
-       BUG_ON(!PageLocked(page));
-       BUG_ON(from > PAGE_CACHE_SIZE);
-       BUG_ON(to > PAGE_CACHE_SIZE);
-       BUG_ON(from > to);
-       BUG_ON(NInoMstProtected(ni));
-       /*
-        * 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;
-                       goto err_out;
-               }
-       }
-       /* If the attribute is not resident, deal with it elsewhere. */
-       if (NInoNonResident(ni)) {
-               /*
-                * Only unnamed $DATA attributes can be compressed, encrypted,
-                * and/or sparse.
-                */
-               if (ni->type == AT_DATA && !ni->name_len) {
-                       /* If file is encrypted, deny access, just like NT4. */
-                       if (NInoEncrypted(ni)) {
-                               ntfs_debug("Denying write access to encrypted "
-                                               "file.");
-                               return -EACCES;
-                       }
-                       /* Compressed data streams are handled in compress.c. */
-                       if (NInoCompressed(ni)) {
-                               // TODO: Implement and replace this check with
-                               // return ntfs_write_compressed_block(page);
-                               ntfs_error(vi->i_sb, "Writing to compressed "
-                                               "files is not supported yet. "
-                                               "Sorry.");
-                               return -EOPNOTSUPP;
-                       }
-                       // TODO: Implement and remove this check.
-                       if (NInoSparse(ni)) {
-                               ntfs_error(vi->i_sb, "Writing to sparse files "
-                                               "is not supported yet. Sorry.");
-                               return -EOPNOTSUPP;
-                       }
-               }
-               /* Normal data stream. */
-               return ntfs_prepare_nonresident_write(page, from, to);
-       }
-       /*
-        * Attribute is resident, implying it is not compressed, encrypted, or
-        * sparse.
-        */
-       BUG_ON(page_has_buffers(page));
-       new_size = ((s64)page->index << PAGE_CACHE_SHIFT) + to;
-       /* If we do not need to resize the attribute allocation we are done. */
-       if (new_size <= i_size_read(vi))
-               goto done;
-       /* Map, pin, and lock the (base) mft 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);
-               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;
-       }
-       m = ctx->mrec;
-       a = ctx->attr;
-       /* The total length of the attribute value. */
-       attr_len = le32_to_cpu(a->data.resident.value_length);
-       /* Fix an eventual previous failure of ntfs_commit_write(). */
-       i_size = i_size_read(vi);
-       if (unlikely(attr_len > i_size)) {
-               attr_len = i_size;
-               a->data.resident.value_length = cpu_to_le32(attr_len);
-       }
-       /* If we do not need to resize the attribute allocation we are done. */
-       if (new_size <= attr_len)
-               goto done_unm;
-       /* Check if new size is allowed in $AttrDef. */
-       err = ntfs_attr_size_bounds_check(vol, ni->type, new_size);
-       if (unlikely(err)) {
-               if (err == -ERANGE) {
-                       ntfs_error(vol->sb, "Write would cause the inode "
-                                       "0x%lx to exceed the maximum size for "
-                                       "its attribute type (0x%x).  Aborting "
-                                       "write.", vi->i_ino,
-                                       le32_to_cpu(ni->type));
-               } else {
-                       ntfs_error(vol->sb, "Inode 0x%lx has unknown "
-                                       "attribute type 0x%x.  Aborting "
-                                       "write.", vi->i_ino,
-                                       le32_to_cpu(ni->type));
-                       err = -EIO;
-               }
-               goto err_out2;
-       }
-       /*
-        * Extend the attribute record to be able to store the new attribute
-        * size.
-        */
-       if (new_size >= vol->mft_record_size || ntfs_attr_record_resize(m, a,
-                       le16_to_cpu(a->data.resident.value_offset) +
-                       new_size)) {
-               /* Not enough space in the mft record. */
-               ntfs_error(vol->sb, "Not enough space in the mft record for "
-                               "the resized attribute value.  This is not "
-                               "supported yet.  Aborting write.");
-               err = -EOPNOTSUPP;
-               goto err_out2;
-       }
-       /*
-        * We have enough space in the mft record to fit the write.  This
-        * implies the attribute is smaller than the mft record and hence the
-        * attribute must be in a single page and hence page->index must be 0.
-        */
-       BUG_ON(page->index);
-       /*
-        * If the beginning of the write is past the old size, enlarge the
-        * attribute value up to the beginning of the write and fill it with
-        * zeroes.
-        */
-       if (from > attr_len) {
-               memset((u8*)a + le16_to_cpu(a->data.resident.value_offset) +
-                               attr_len, 0, from - attr_len);
-               a->data.resident.value_length = cpu_to_le32(from);
-               /* Zero the corresponding area in the page as well. */
-               if (PageUptodate(page)) {
-                       kaddr = kmap_atomic(page, KM_USER0);
-                       memset(kaddr + attr_len, 0, from - attr_len);
-                       kunmap_atomic(kaddr, KM_USER0);
-                       flush_dcache_page(page);
-               }
-       }
-       flush_dcache_mft_record_page(ctx->ntfs_ino);
-       mark_mft_record_dirty(ctx->ntfs_ino);
-done_unm:
-       ntfs_attr_put_search_ctx(ctx);
-       unmap_mft_record(base_ni);
-       /*
-        * Because resident attributes are handled by memcpy() to/from the
-        * corresponding MFT record, and because this form of i/o is byte
-        * aligned rather than block aligned, there is no need to bring the
-        * page uptodate here as in the non-resident case where we need to
-        * bring the buffers straddled by the write uptodate before
-        * generic_file_write() does the copying from userspace.
-        *
-        * We thus defer the uptodate bringing of the page region outside the
-        * region written to to ntfs_commit_write(), which makes the code
-        * simpler and saves one atomic kmap which is good.
-        */
-done:
-       ntfs_debug("Done.");
-       return 0;
-err_out:
-       if (err == -ENOMEM)
-               ntfs_warning(vi->i_sb, "Error allocating memory required to "
-                               "prepare the write.");
-       else {
-               ntfs_error(vi->i_sb, "Resident attribute prepare write failed "
-                               "with error %i.", err);
-               NVolSetErrors(vol);
-               make_bad_inode(vi);
-       }
-err_out2:
-       if (ctx)
-               ntfs_attr_put_search_ctx(ctx);
-       if (m)
-               unmap_mft_record(base_ni);
-       return err;
-}
-
-/**
- * ntfs_commit_nonresident_write -
- *
- */
-static int ntfs_commit_nonresident_write(struct page *page,
-               unsigned from, unsigned to)
-{
-       s64 pos = ((s64)page->index << PAGE_CACHE_SHIFT) + to;
-       struct inode *vi = page->mapping->host;
-       struct buffer_head *bh, *head;
-       unsigned int block_start, block_end, blocksize;
-       BOOL partial;
-
-       ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
-                       "0x%lx, from = %u, to = %u.", vi->i_ino,
-                       NTFS_I(vi)->type, page->index, from, to);
-       blocksize = 1 << vi->i_blkbits;
-
-       // FIXME: We need a whole slew of special cases in here for compressed
-       // files for example...
-       // For now, we know ntfs_prepare_write() would have failed so we can't
-       // get here in any of the cases which we have to special case, so we
-       // are just a ripped off, unrolled generic_commit_write().
-
-       bh = head = page_buffers(page);
-       block_start = 0;
-       partial = FALSE;
-       do {
-               block_end = block_start + blocksize;
-               if (block_end <= from || block_start >= to) {
-                       if (!buffer_uptodate(bh))
-                               partial = TRUE;
-               } else {
-                       set_buffer_uptodate(bh);
-                       mark_buffer_dirty(bh);
-               }
-       } while (block_start = block_end, (bh = bh->b_this_page) != head);
-       /*
-        * If this is a partial write which happened to make all buffers
-        * uptodate then we can optimize away a bogus ->readpage() for the next
-        * read().  Here we 'discover' whether the page went uptodate as a
-        * result of this (potentially partial) write.
-        */
-       if (!partial)
-               SetPageUptodate(page);
-       /*
-        * Not convinced about this at all.  See disparity comment above.  For
-        * now we know ntfs_prepare_write() would have failed in the write
-        * exceeds i_size case, so this will never trigger which is fine.
-        */
-       if (pos > i_size_read(vi)) {
-               ntfs_error(vi->i_sb, "Writing beyond the existing file size is "
-                               "not supported yet.  Sorry.");
-               return -EOPNOTSUPP;
-               // vi->i_size = pos;
-               // mark_inode_dirty(vi);
-       }
-       ntfs_debug("Done.");
-       return 0;
-}
-
-/**
- * ntfs_commit_write - commit the received data
- *
- * This is called from generic_file_write() with i_sem held on the inode
- * (@page->mapping->host).  The @page is locked but not kmap()ped.  The source
- * data has already been copied into the @page.  ntfs_prepare_write() has been
- * called before the data copied and it returned success so we can take the
- * results of various BUG checks and some error handling for granted.
- *
- * Need to mark modified blocks dirty so they get written out later when
- * ntfs_writepage() is invoked by the VM.
- *
- * Return 0 on success or -errno on error.
- *
- * Should be using generic_commit_write().  This 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.
- *
- * Cannot use generic_commit_write() due to ntfs specialities but can look at
- * it for implementation guidance.
- *
- * If things have gone as outlined in ntfs_prepare_write(), then we do not
- * need to do any page content modifications here at all, except in the write
- * to resident attribute case, where 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.
- */
-static int ntfs_commit_write(struct file *file, struct page *page,
-               unsigned from, unsigned to)
-{
-       struct inode *vi = page->mapping->host;
-       ntfs_inode *base_ni, *ni = NTFS_I(vi);
-       char *kaddr, *kattr;
-       ntfs_attr_search_ctx *ctx;
-       MFT_RECORD *m;
-       ATTR_RECORD *a;
-       u32 attr_len;
-       int err;
-
-       ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
-                       "0x%lx, from = %u, to = %u.", vi->i_ino, ni->type,
-                       page->index, from, to);
-       /* If the attribute is not resident, deal with it elsewhere. */
-       if (NInoNonResident(ni)) {
-               /* Only unnamed $DATA attributes can be compressed/encrypted. */
-               if (ni->type == AT_DATA && !ni->name_len) {
-                       /* Encrypted files need separate handling. */
-                       if (NInoEncrypted(ni)) {
-                               // We never get here at present!
-                               BUG();
-                       }
-                       /* Compressed data streams are handled in compress.c. */
-                       if (NInoCompressed(ni)) {
-                               // TODO: Implement this!
-                               // return ntfs_write_compressed_block(page);
-                               // We never get here at present!
-                               BUG();
-                       }
-               }
-               /* Normal data stream. */
-               return ntfs_commit_nonresident_write(page, from, to);
-       }
-       /*
-        * 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;
-       /* 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;
-       /* The total length of the attribute value. */
-       attr_len = le32_to_cpu(a->data.resident.value_length);
-       BUG_ON(from > attr_len);
-       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 + from, kaddr + from, to - from);
-       /* Update the attribute length if necessary. */
-       if (to > attr_len) {
-               attr_len = to;
-               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 (from > 0)
-                       memcpy(kaddr, kattr, from);
-               if (to < attr_len)
-                       memcpy(kaddr + to, kattr + to, attr_len - to);
-               /* Zero the region outside the end of the attribute value. */
-               if (attr_len < PAGE_CACHE_SIZE)
-                       memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
-               /*
-                * The probability of not having done any of the above is
-                * extremely small, so we just flush unconditionally.
-                */
-               flush_dcache_page(page);
-               SetPageUptodate(page);
-       }
-       kunmap_atomic(kaddr, KM_USER0);
-       /* Update i_size if necessary. */
-       if (i_size_read(vi) < attr_len) {
-               unsigned long flags;
-
-               write_lock_irqsave(&ni->size_lock, flags);
-               ni->allocated_size = ni->initialized_size = attr_len;
-               i_size_write(vi, attr_len);
-               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);
-               make_bad_inode(vi);
-       }
-       if (ctx)
-               ntfs_attr_put_search_ctx(ctx);
-       if (m)
-               unmap_mft_record(base_ni);
-       return err;
-}
-
 #endif /* NTFS_RW */
 
 /**
@@ -2377,9 +1553,6 @@ struct address_space_operations ntfs_aops = {
                                                   disk request queue. */
 #ifdef NTFS_RW
        .writepage      = ntfs_writepage,       /* Write dirty page to disk. */
-       .prepare_write  = ntfs_prepare_write,   /* Prepare page and buffers
-                                                  ready to receive data. */
-       .commit_write   = ntfs_commit_write,    /* Commit received data. */
 #endif /* NTFS_RW */
 };