cifs: don't leak -EAGAIN for stat() during reconnect
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Message ID 20200218044829.15629-1-lsahlber@redhat.com
State New
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Series
  • cifs: don't leak -EAGAIN for stat() during reconnect
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Commit Message

Ronnie Sahlberg Feb. 18, 2020, 4:48 a.m. UTC
If from cifs_revalidate_dentry_attr() the SMB2/QUERY_INFO call fails with an
error, such as STATUS_SESSION_EXPIRED, causing the session to be reconnected
it is possible we will leak -EAGAIN back to the application even for
system calls such as stat() where this is not a valid error.

Fix this by re-trying the operation from within cifs_revalidate_dentry_attr()
if cifs_get_inode_info*() returns -EAGAIN.

This fixes stat() and possibly also other system calls that uses
cifs_revalidate_dentry*().

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
---
 fs/cifs/inode.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Comments

Aurélien Aptel Feb. 18, 2020, 11:47 a.m. UTC | #1
Hi Ronnie,

Ronnie Sahlberg <lsahlber@redhat.com> writes:
> Fix this by re-trying the operation from within cifs_revalidate_dentry_attr()
> if cifs_get_inode_info*() returns -EAGAIN.

Would it make sense to use is_retryable_error() instead of checking for
just EAGAIN? It also checks for interruption errors.

Cheers,
ronnie sahlberg Feb. 18, 2020, 7:58 p.m. UTC | #2
On Tue, Feb 18, 2020 at 9:47 PM Aurélien Aptel <aaptel@suse.com> wrote:
>
> Hi Ronnie,
>
> Ronnie Sahlberg <lsahlber@redhat.com> writes:
> > Fix this by re-trying the operation from within cifs_revalidate_dentry_attr()
> > if cifs_get_inode_info*() returns -EAGAIN.
>
> Would it make sense to use is_retryable_error() instead of checking for
> just EAGAIN? It also checks for interruption errors.

Makes sense. Thanks.

>
> Cheers,
> --
> Aurélien Aptel / SUSE Labs Samba Team
> GPG: 1839 CB5F 9F5B FB9B AA97  8C99 03C8 A49B 521B D5D3
> SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg, DE
> GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 247165 (AG München)

Patch
diff mbox series

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index b5e6635c578e..1c6f659110d0 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -2073,6 +2073,7 @@  int cifs_revalidate_dentry_attr(struct dentry *dentry)
 	struct inode *inode = d_inode(dentry);
 	struct super_block *sb = dentry->d_sb;
 	char *full_path = NULL;
+	int count = 0;
 
 	if (inode == NULL)
 		return -ENOENT;
@@ -2094,15 +2095,18 @@  int cifs_revalidate_dentry_attr(struct dentry *dentry)
 		 full_path, inode, inode->i_count.counter,
 		 dentry, cifs_get_time(dentry), jiffies);
 
+again:
 	if (cifs_sb_master_tcon(CIFS_SB(sb))->unix_ext)
 		rc = cifs_get_inode_info_unix(&inode, full_path, sb, xid);
 	else
 		rc = cifs_get_inode_info(&inode, full_path, NULL, sb,
 					 xid, NULL);
-
+	if (rc == -EAGAIN && count++ < 10)
+		goto again;
 out:
 	kfree(full_path);
 	free_xid(xid);
+
 	return rc;
 }