PING again Thanks, NeilBrown On Fri, Jul 22 2016, NeilBrown wrote: > PING .... any comments on this patch, or the problem it tries to > address? > > Thanks, > NeilBrown > > > On Fri, Jun 03 2016, NeilBrown wrote: > >> When a byte range lock (or flock) is taken out on an NFS file, the >> validity of the cached data is checked and the inode is marked >> NFS_INODE_INVALID_DATA. However the cached data isn't flushed from >> the page cache. >> >> This is sufficient for future read() requests or mmap() requests as >> they call nfs_revalidate_mapping() which performs the flush if >> necessary. >> >> However an existing mapping is not affected. Accessing data through >> that mapping will continue to return old data even though the inode is >> marked NFS_INODE_INVALID_DATA. >> >> This can easily be confirmed using the 'nfs' tool in >> git://github.com/okirch/twopence-nfs.git >> and running >> >> nfs coherence FILENAME >> on one client, and >> nfs coherence -r FILENAME >> on another client. >> >> It appears that prior to Linux 2.6.0 this worked correctly. >> >> However commit: >> >> http://git.kernel.org/cgit/linux/kernel/git/history/history.git/commit/?id=ca9268fe3ddd075714005adecd4afbd7f9ab87d0 >> >> removed the call to inode_invalidate_pages() from nfs_zap_caches(). I >> haven't tested this code, but inspection suggests that prior to this >> commit, file locking would invalidate all inode pages. >> >> This patch adds a call to nfs_revalidate_mapping_protected() after a >> successful SETLK so that invalid data is flushed. With this patch the >> above test passes. >> >> Cc: Olaf Kirch <okir@xxxxxxxx> >> Signed-off-by: NeilBrown <neilb@xxxxxxxx> >> --- >> fs/nfs/file.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/fs/nfs/file.c b/fs/nfs/file.c >> index 717a8d6af52d..781cc6c9c60b 100644 >> --- a/fs/nfs/file.c >> +++ b/fs/nfs/file.c >> @@ -822,6 +822,7 @@ do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local) >> __nfs_revalidate_inode(NFS_SERVER(inode), inode); >> else >> nfs_zap_caches(inode); >> + nfs_revalidate_mapping_protected(inode, filp->f_mapping); >> } >> out: >> return status; >> -- >> 2.8.3
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