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NFS: Judge the file access cache's timestamp in rcu path

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If the user's login time is newer than the cache's timestamp,
we expect the cache may be stale and need to clear.
The stale cache will remain in the list's tail if no other
users operate on that inode.
Once the user accesses the inode, the stale cache will be
returned in rcu path.

Signed-off-by: Chengen Du <chengen.du@canonical.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Chengen Du 2022-12-30 11:04:32 +08:00 committed by Trond Myklebust
parent a6b9d2fa00
commit 029085b894
1 changed files with 3 additions and 0 deletions
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3
fs/nfs/dir.c
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@ -3023,6 +3023,7 @@ static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cre
* but do it without locking.
*/
struct nfs_inode *nfsi = NFS_I(inode);
u64 login_time = nfs_access_login_time(current, cred);
struct nfs_access_entry *cache;
int err = -ECHILD;
struct list_head *lh;
@ -3037,6 +3038,8 @@ static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cre
cache = NULL;
if (cache == NULL)
goto out;
if ((s64)(login_time - cache->timestamp) > 0)
goto out;
if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS))
goto out;
*mask = cache->mask;