From 37d9d76d8b3a2ac5817e1fa3263cfe0fdb439e51 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Wed, 11 Mar 2009 14:10:23 -0400 Subject: [PATCH] NFS: flush cached directory information slightly more readily. If cached directory contents becomes incorrect, there is no way to flush the contents. This contrasts with files where file locking is the recommended way to ensure cache consistency between multiple applications (a read-lock always flushes the cache). Also while changes to files often change the size of the file (thus triggering a cache flush), changes to directories often do not change the apparent size (as the size is often rounded to a block size). So it is particularly important with directories to avoid the possibility of an incorrect cache wherever possible. When the link count on a directory changes it implies a change in the number of child directories, and so a change in the contents of this directory. So use that as a trigger to flush cached contents. When the ctime changes but the mtime does not, there are two possible reasons. 1/ The owner/mode information has been changed. 2/ utimes has been used to set the mtime backwards. In the first case, a data-cache flush is not required. In the second case it is. So on the basis that correctness trumps performance, flush the directory contents cache in this case also. Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust --- fs/nfs/inode.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index acaaa7c7efa4..268ce3a46220 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -1113,8 +1113,16 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr) nfs_force_lookup_revalidate(inode); } /* If ctime has changed we should definitely clear access+acl caches */ - if (!timespec_equal(&inode->i_ctime, &fattr->ctime)) + if (!timespec_equal(&inode->i_ctime, &fattr->ctime)) { invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL; + /* and probably clear data for a directory too as utimes can cause + * havoc with our cache. + */ + if (S_ISDIR(inode->i_mode)) { + invalid |= NFS_INO_INVALID_DATA; + nfs_force_lookup_revalidate(inode); + } + } } else if (nfsi->change_attr != fattr->change_attr) { dprintk("NFS: change_attr change on server for file %s/%ld\n", inode->i_sb->s_id, inode->i_ino); @@ -1148,8 +1156,11 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr) inode->i_gid != fattr->gid) invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL; - if (inode->i_nlink != fattr->nlink) + if (inode->i_nlink != fattr->nlink) { invalid |= NFS_INO_INVALID_ATTR; + if (S_ISDIR(inode->i_mode)) + invalid |= NFS_INO_INVALID_DATA; + } inode->i_mode = fattr->mode; inode->i_nlink = fattr->nlink;