From a4ff7401fbfa06fba3aac14db5b33c5b76298f2c Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 6 Apr 2018 14:17:24 +0100 Subject: [PATCH] afs: Keep track of invalid-before version for dentry coherency Each afs dentry is tagged with the version that the parent directory was at last time it was validated and, currently, if this differs, the directory is scanned and the dentry is refreshed. However, this leads to an excessive amount of revalidation on directories that get modified on the client without conflict with another client. We know there's no conflict because the parent directory's data version number got incremented by exactly 1 on any create, mkdir, unlink, etc., therefore we can trust the current state of the unaffected dentries when we perform a local directory modification. Optimise by keeping track of the last version of the parent directory that was changed outside of the client in the parent directory's vnode and using that to validate the dentries rather than the current version. Signed-off-by: David Howells --- fs/afs/dir.c | 20 +++++++++++++++----- fs/afs/fsclient.c | 1 + fs/afs/inode.c | 1 + fs/afs/internal.h | 1 + 4 files changed, 18 insertions(+), 5 deletions(-) diff --git a/fs/afs/dir.c b/fs/afs/dir.c index 538ca18efe0d82..08b499504f6325 100644 --- a/fs/afs/dir.c +++ b/fs/afs/dir.c @@ -1015,7 +1015,7 @@ static int afs_d_revalidate(struct dentry *dentry, unsigned int flags) struct dentry *parent; struct inode *inode; struct key *key; - void *dir_version; + long dir_version, de_version; int ret; if (flags & LOOKUP_RCU) @@ -1059,9 +1059,19 @@ static int afs_d_revalidate(struct dentry *dentry, unsigned int flags) goto out_bad_parent; } - dir_version = (void *) (unsigned long) dir->status.data_version; - if (dentry->d_fsdata == dir_version) - goto out_valid; /* the dir contents are unchanged */ + /* We only need to invalidate a dentry if the server's copy changed + * behind our back. If we made the change, it's no problem. Note that + * on a 32-bit system, we only have 32 bits in the dentry to store the + * version. + */ + dir_version = (long)dir->status.data_version; + de_version = (long)dentry->d_fsdata; + if (de_version == dir_version) + goto out_valid; + + dir_version = (long)dir->invalid_before; + if (de_version - dir_version >= 0) + goto out_valid; _debug("dir modified"); afs_stat_v(dir, n_reval); @@ -1120,7 +1130,7 @@ static int afs_d_revalidate(struct dentry *dentry, unsigned int flags) } out_valid: - dentry->d_fsdata = dir_version; + dentry->d_fsdata = (void *)dir_version; dput(parent); key_put(key); _leave(" = 1 [valid]"); diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c index ff87fc6bb27fbb..f7570d229dcc4d 100644 --- a/fs/afs/fsclient.c +++ b/fs/afs/fsclient.c @@ -100,6 +100,7 @@ void afs_update_inode_from_status(struct afs_vnode *vnode, (unsigned long long) status->data_version, vnode->fid.vid, vnode->fid.vnode, (unsigned long long) *expected_version); + vnode->invalid_before = status->data_version; set_bit(AFS_VNODE_DIR_MODIFIED, &vnode->flags); set_bit(AFS_VNODE_ZAP_DATA, &vnode->flags); } diff --git a/fs/afs/inode.c b/fs/afs/inode.c index 2e32d475ec11f5..07f450513f3e95 100644 --- a/fs/afs/inode.c +++ b/fs/afs/inode.c @@ -83,6 +83,7 @@ static int afs_inode_init_from_status(struct afs_vnode *vnode, struct key *key) inode->i_blocks = 0; inode->i_mapping->a_ops = &afs_fs_aops; + vnode->invalid_before = vnode->status.data_version; read_sequnlock_excl(&vnode->cb_lock); diff --git a/fs/afs/internal.h b/fs/afs/internal.h index ac3076c2a8e827..adf9b17d328c1b 100644 --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -479,6 +479,7 @@ struct afs_vnode { struct afs_volume *volume; /* volume on which vnode resides */ struct afs_fid fid; /* the file identifier for this inode */ struct afs_file_status status; /* AFS status info for this file */ + afs_dataversion_t invalid_before; /* Child dentries are invalid before this */ #ifdef CONFIG_AFS_FSCACHE struct fscache_cookie *cache; /* caching cookie */ #endif