cifs: report error instead of invalid when revalidating a dentry fails

commit 21b200d091826a83aafc95d847139b2b0582f6d1 upstream.

Assuming
- //HOST/a is mounted on /mnt
- //HOST/b is mounted on /mnt/b

On a slow connection, running 'df' and killing it while it's
processing /mnt/b can make cifs_get_inode_info() returns -ERESTARTSYS.

This triggers the following chain of events:
=> the dentry revalidation fail
=> dentry is put and released
=> superblock associated with the dentry is put
=> /mnt/b is unmounted

This patch makes cifs_d_revalidate() return the error instead of 0
(invalid) when cifs_revalidate_dentry() fails, except for ENOENT (file
deleted) and ESTALE (file recreated).

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Suggested-by: Shyam Prasad N <nspmangalore@gmail.com>
Reviewed-by: Shyam Prasad N <nspmangalore@gmail.com>
CC: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Aurelien Aptel 2021-02-05 15:42:48 +01:00 committed by Greg Kroah-Hartman
parent c026844c61
commit 7a3361e5ec

View File

@ -736,6 +736,7 @@ static int
cifs_d_revalidate(struct dentry *direntry, unsigned int flags) cifs_d_revalidate(struct dentry *direntry, unsigned int flags)
{ {
struct inode *inode; struct inode *inode;
int rc;
if (flags & LOOKUP_RCU) if (flags & LOOKUP_RCU)
return -ECHILD; return -ECHILD;
@ -745,8 +746,25 @@ cifs_d_revalidate(struct dentry *direntry, unsigned int flags)
if ((flags & LOOKUP_REVAL) && !CIFS_CACHE_READ(CIFS_I(inode))) if ((flags & LOOKUP_REVAL) && !CIFS_CACHE_READ(CIFS_I(inode)))
CIFS_I(inode)->time = 0; /* force reval */ CIFS_I(inode)->time = 0; /* force reval */
if (cifs_revalidate_dentry(direntry)) rc = cifs_revalidate_dentry(direntry);
return 0; if (rc) {
cifs_dbg(FYI, "cifs_revalidate_dentry failed with rc=%d", rc);
switch (rc) {
case -ENOENT:
case -ESTALE:
/*
* Those errors mean the dentry is invalid
* (file was deleted or recreated)
*/
return 0;
default:
/*
* Otherwise some unexpected error happened
* report it as-is to VFS layer
*/
return rc;
}
}
else { else {
/* /*
* If the inode wasn't known to be a dfs entry when * If the inode wasn't known to be a dfs entry when