Commit 57659a80 authored Feb 05, 2021 by Aurelien Aptel Committed by Greg Kroah-Hartman Feb 10, 2021

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>

parent 9d9f8bb2

fs/cifs/dir.c

+20 −2

Original line number	Diff line number	Diff line
		@@ -830,6 +830,7 @@ static int
		cifs_d_revalidate(struct dentry *direntry, unsigned int flags)
		{
		struct inode *inode;
		int rc;

		if (flags & LOOKUP_RCU)
		return -ECHILD;
		@@ -839,8 +840,25 @@ cifs_d_revalidate(struct dentry *direntry, unsigned int flags)
		if ((flags & LOOKUP_REVAL) && !CIFS_CACHE_READ(CIFS_I(inode)))
		CIFS_I(inode)->time = 0; /* force reval */

		if (cifs_revalidate_dentry(direntry))
		rc = cifs_revalidate_dentry(direntry);
		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 {
		/*
		* If the inode wasn't known to be a dfs entry when