fs/9p: Add buffered write support for v9fs.
Aneesh Kumar K.V [Mon, 28 Feb 2011 11:33:58 +0000 (16:33 +0530)]
We can now support writeable mmaps.
Based on the original patch from Badari Pulavarty <pbadari@us.ibm.com>

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

fs/9p/vfs_addr.c
fs/9p/vfs_file.c

index 637bd70..566684c 100644 (file)
 #include "v9fs.h"
 #include "v9fs_vfs.h"
 #include "cache.h"
+#include "fid.h"
 
 /**
- * v9fs_vfs_readpage - read an entire page in from 9P
+ * v9fs_fid_readpage - read an entire page in from 9P
  *
- * @filp: file being read
+ * @fid: fid being read
  * @page: structure to page
  *
  */
-
-static int v9fs_vfs_readpage(struct file *filp, struct page *page)
+static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page)
 {
        int retval;
        loff_t offset;
@@ -67,7 +67,7 @@ static int v9fs_vfs_readpage(struct file *filp, struct page *page)
        buffer = kmap(page);
        offset = page_offset(page);
 
-       retval = v9fs_file_readn(filp, buffer, NULL, PAGE_CACHE_SIZE, offset);
+       retval = v9fs_fid_readn(fid, buffer, NULL, PAGE_CACHE_SIZE, offset);
        if (retval < 0) {
                v9fs_uncache_page(inode, page);
                goto done;
@@ -87,6 +87,19 @@ done:
 }
 
 /**
+ * v9fs_vfs_readpage - read an entire page in from 9P
+ *
+ * @filp: file being read
+ * @page: structure to page
+ *
+ */
+
+static int v9fs_vfs_readpage(struct file *filp, struct page *page)
+{
+       return v9fs_fid_readpage(filp->private_data, page);
+}
+
+/**
  * v9fs_vfs_readpages - read a set of pages from 9P
  *
  * @filp: file being read
@@ -124,7 +137,6 @@ static int v9fs_release_page(struct page *page, gfp_t gfp)
 {
        if (PagePrivate(page))
                return 0;
-
        return v9fs_fscache_release_page(page, gfp);
 }
 
@@ -137,22 +149,87 @@ static int v9fs_release_page(struct page *page, gfp_t gfp)
 
 static void v9fs_invalidate_page(struct page *page, unsigned long offset)
 {
+       /*
+        * If called with zero offset, we should release
+        * the private state assocated with the page
+        */
        if (offset == 0)
                v9fs_fscache_invalidate_page(page);
 }
 
+static int v9fs_vfs_writepage_locked(struct page *page)
+{
+       char *buffer;
+       int retval, len;
+       loff_t offset, size;
+       mm_segment_t old_fs;
+       struct inode *inode = page->mapping->host;
+
+       size = i_size_read(inode);
+       if (page->index == size >> PAGE_CACHE_SHIFT)
+               len = size & ~PAGE_CACHE_MASK;
+       else
+               len = PAGE_CACHE_SIZE;
+
+       set_page_writeback(page);
+
+       buffer = kmap(page);
+       offset = page_offset(page);
+
+       old_fs = get_fs();
+       set_fs(get_ds());
+       /* We should have i_private always set */
+       BUG_ON(!inode->i_private);
+
+       retval = v9fs_file_write_internal(inode,
+                                         (struct p9_fid *)inode->i_private,
+                                         (__force const char __user *)buffer,
+                                         len, &offset, 0);
+       if (retval > 0)
+               retval = 0;
+
+       set_fs(old_fs);
+       kunmap(page);
+       end_page_writeback(page);
+       return retval;
+}
+
+static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+       int retval;
+
+       retval = v9fs_vfs_writepage_locked(page);
+       if (retval < 0) {
+               if (retval == -EAGAIN) {
+                       redirty_page_for_writepage(wbc, page);
+                       retval = 0;
+               } else {
+                       SetPageError(page);
+                       mapping_set_error(page->mapping, retval);
+               }
+       } else
+               retval = 0;
+
+       unlock_page(page);
+       return retval;
+}
+
 /**
  * v9fs_launder_page - Writeback a dirty page
- * Since the writes go directly to the server, we simply return a 0
- * here to indicate success.
- *
  * Returns 0 on success.
  */
 
 static int v9fs_launder_page(struct page *page)
 {
+       int retval;
        struct inode *inode = page->mapping->host;
+
        v9fs_fscache_wait_on_page_write(inode, page);
+       if (clear_page_dirty_for_io(page)) {
+               retval = v9fs_vfs_writepage_locked(page);
+               if (retval)
+                       return retval;
+       }
        return 0;
 }
 
@@ -178,6 +255,11 @@ static int v9fs_launder_page(struct page *page)
 ssize_t v9fs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
                loff_t pos, unsigned long nr_segs)
 {
+       /*
+        * FIXME
+        * Now that we do caching with cache mode enabled, We need
+        * to support direct IO
+        */
        P9_DPRINTK(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) "
                        "off/no(%lld/%lu) EINVAL\n",
                        iocb->ki_filp->f_path.dentry->d_name.name,
@@ -185,11 +267,82 @@ ssize_t v9fs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 
        return -EINVAL;
 }
+
+static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
+                           loff_t pos, unsigned len, unsigned flags,
+                           struct page **pagep, void **fsdata)
+{
+       int retval = 0;
+       struct page *page;
+       pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+       struct inode *inode = mapping->host;
+
+start:
+       page = grab_cache_page_write_begin(mapping, index, flags);
+       if (!page) {
+               retval = -ENOMEM;
+               goto out;
+       }
+       BUG_ON(!inode->i_private);
+       if (PageUptodate(page))
+               goto out;
+
+       if (len == PAGE_CACHE_SIZE)
+               goto out;
+
+       retval = v9fs_fid_readpage(inode->i_private, page);
+       page_cache_release(page);
+       if (!retval)
+               goto start;
+out:
+       *pagep = page;
+       return retval;
+}
+
+static int v9fs_write_end(struct file *filp, struct address_space *mapping,
+                         loff_t pos, unsigned len, unsigned copied,
+                         struct page *page, void *fsdata)
+{
+       loff_t last_pos = pos + copied;
+       struct inode *inode = page->mapping->host;
+
+       if (unlikely(copied < len)) {
+               /*
+                * zero out the rest of the area
+                */
+               unsigned from = pos & (PAGE_CACHE_SIZE - 1);
+
+               zero_user(page, from + copied, len - copied);
+               flush_dcache_page(page);
+       }
+
+       if (!PageUptodate(page))
+               SetPageUptodate(page);
+       /*
+        * No need to use i_size_read() here, the i_size
+        * cannot change under us because we hold the i_mutex.
+        */
+       if (last_pos > inode->i_size) {
+               inode_add_bytes(inode, last_pos - inode->i_size);
+               i_size_write(inode, last_pos);
+       }
+       set_page_dirty(page);
+       unlock_page(page);
+       page_cache_release(page);
+
+       return copied;
+}
+
+
 const struct address_space_operations v9fs_addr_operations = {
-      .readpage = v9fs_vfs_readpage,
-      .readpages = v9fs_vfs_readpages,
-      .releasepage = v9fs_release_page,
-      .invalidatepage = v9fs_invalidate_page,
-      .launder_page = v9fs_launder_page,
-      .direct_IO = v9fs_direct_IO,
+       .readpage = v9fs_vfs_readpage,
+       .readpages = v9fs_vfs_readpages,
+       .set_page_dirty = __set_page_dirty_nobuffers,
+       .writepage = v9fs_vfs_writepage,
+       .write_begin = v9fs_write_begin,
+       .write_end = v9fs_write_end,
+       .releasepage = v9fs_release_page,
+       .invalidatepage = v9fs_invalidate_page,
+       .launder_page = v9fs_launder_page,
+       .direct_IO = v9fs_direct_IO,
 };
index e966f15..f7b571d 100644 (file)
@@ -44,6 +44,8 @@
 #include "fid.h"
 #include "cache.h"
 
+static const struct vm_operations_struct v9fs_file_vm_ops;
+
 /**
  * v9fs_file_open - open a file (or directory)
  * @inode: inode to be opened
@@ -503,6 +505,7 @@ out:
        return retval;
 }
 
+
 static int v9fs_file_fsync(struct file *filp, int datasync)
 {
        struct p9_fid *fid;
@@ -532,28 +535,71 @@ int v9fs_file_fsync_dotl(struct file *filp, int datasync)
        return retval;
 }
 
+static int
+v9fs_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+       int retval;
+
+       retval = generic_file_mmap(file, vma);
+       if (!retval)
+               vma->vm_ops = &v9fs_file_vm_ops;
+
+       return retval;
+}
+
+static int
+v9fs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+       struct page *page = vmf->page;
+       struct file *filp = vma->vm_file;
+       struct inode *inode = filp->f_path.dentry->d_inode;
+
+
+       P9_DPRINTK(P9_DEBUG_VFS, "page %p fid %lx\n",
+                  page, (unsigned long)filp->private_data);
+
+       /* make sure the cache has finished storing the page */
+       v9fs_fscache_wait_on_page_write(inode, page);
+       BUG_ON(!inode->i_private);
+       lock_page(page);
+       if (page->mapping != inode->i_mapping)
+               goto out_unlock;
+
+       return VM_FAULT_LOCKED;
+out_unlock:
+       unlock_page(page);
+       return VM_FAULT_NOPAGE;
+}
+
+static const struct vm_operations_struct v9fs_file_vm_ops = {
+       .fault = filemap_fault,
+       .page_mkwrite = v9fs_vm_page_mkwrite,
+};
+
 const struct file_operations v9fs_cached_file_operations = {
        .llseek = generic_file_llseek,
        .read = do_sync_read,
+       .write = do_sync_write,
        .aio_read = generic_file_aio_read,
-       .write = v9fs_file_write,
+       .aio_write = generic_file_aio_write,
        .open = v9fs_file_open,
        .release = v9fs_dir_release,
        .lock = v9fs_file_lock,
-       .mmap = generic_file_readonly_mmap,
+       .mmap = v9fs_file_mmap,
        .fsync = v9fs_file_fsync,
 };
 
 const struct file_operations v9fs_cached_file_operations_dotl = {
        .llseek = generic_file_llseek,
        .read = do_sync_read,
+       .write = do_sync_write,
        .aio_read = generic_file_aio_read,
-       .write = v9fs_file_write,
+       .aio_write = generic_file_aio_write,
        .open = v9fs_file_open,
        .release = v9fs_dir_release,
        .lock = v9fs_file_lock_dotl,
        .flock = v9fs_file_flock_dotl,
-       .mmap = generic_file_readonly_mmap,
+       .mmap = v9fs_file_mmap,
        .fsync = v9fs_file_fsync_dotl,
 };