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-rw-r--r--fs/nfs/write.c20
1 files changed, 17 insertions, 3 deletions
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index b144b19..f55c437 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -697,6 +697,17 @@ int nfs_flush_incompatible(struct file *file, struct page *page)
}
/*
+ * If the page cache is marked as unsafe or invalid, then we can't rely on
+ * the PageUptodate() flag. In this case, we will need to turn off
+ * write optimisations that depend on the page contents being correct.
+ */
+static int nfs_write_pageuptodate(struct page *page, struct inode *inode)
+{
+ return PageUptodate(page) &&
+ !(NFS_I(inode)->cache_validity & (NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_DATA));
+}
+
+/*
* Update and possibly write a cached page of an NFS file.
*
* XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
@@ -717,10 +728,13 @@ int nfs_updatepage(struct file *file, struct page *page,
(long long)(page_offset(page) +offset));
/* If we're not using byte range locks, and we know the page
- * is entirely in cache, it may be more efficient to avoid
- * fragmenting write requests.
+ * is up to date, it may be more efficient to extend the write
+ * to cover the entire page in order to avoid fragmentation
+ * inefficiencies.
*/
- if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
+ if (nfs_write_pageuptodate(page, inode) &&
+ inode->i_flock == NULL &&
+ !(file->f_mode & O_SYNC)) {
count = max(count + offset, nfs_page_length(page));
offset = 0;
}
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