3.11.10.4 -stable review patch. If anyone has any objections, please let me know.
------------------ From: Scott Mayhew <[email protected]> commit 263b4509ec4d47e0da3e753f85a39ea12d1eff24 upstream. We should always make sure the cached page is up-to-date when we're determining whether we can extend a write to cover the full page -- even if we've received a write delegation from the server. Commit c7559663 added logic to skip this check if we have a write delegation, which can lead to data corruption such as the following scenario if client B receives a write delegation from the NFS server: Client A: # echo 123456789 > /mnt/file Client B: # echo abcdefghi >> /mnt/file # cat /mnt/file 0�D0�abcdefghi Just because we hold a write delegation doesn't mean that we've read in the entire page contents. Signed-off-by: Scott Mayhew <[email protected]> Signed-off-by: Trond Myklebust <[email protected]> Signed-off-by: Luis Henriques <[email protected]> --- fs/nfs/write.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/fs/nfs/write.c b/fs/nfs/write.c index f1bdb72..058d64c 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -893,19 +893,20 @@ out: * extend the write to cover the entire page in order to avoid fragmentation * inefficiencies. * - * If the file is opened for synchronous writes or if we have a write delegation - * from the server then we can just skip the rest of the checks. + * If the file is opened for synchronous writes then we can just skip the rest + * of the checks. */ static int nfs_can_extend_write(struct file *file, struct page *page, struct inode *inode) { if (file->f_flags & O_DSYNC) return 0; + if (!nfs_write_pageuptodate(page, inode)) + return 0; if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE)) return 1; - if (nfs_write_pageuptodate(page, inode) && (inode->i_flock == NULL || - (inode->i_flock->fl_start == 0 && + if (inode->i_flock == NULL || (inode->i_flock->fl_start == 0 && inode->i_flock->fl_end == OFFSET_MAX && - inode->i_flock->fl_type != F_RDLCK))) + inode->i_flock->fl_type != F_RDLCK)) return 1; return 0; } -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
