Attachment 580329 Details for Bug 786149 – Patch - check S_AUTOMOUNT in revalidate (against current source)

[patch] Patch - check S_AUTOMOUNT in revalidate (against current source)

cifs-check-s_automount-in-revalidate.patch (text/plain), 1.80 KB, created by Ian Kent on 2012-04-26 02:22:18 UTC

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Creator: Ian Kent

Created: 2012-04-26 02:22:18 UTC

Size: 1.80 KB

patch

obsolete

>cifs - check S_AUTOMOUNT in revalidate
>
>From: Ian Kent <ikent@redhat.com>
>
>Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=786149
>
>When revalidating a dentry, if the inode wasn't known to be a dfs
>entry when the dentry was instantiated, such as when created via
>->readdir(), the DCACHE_NEED_AUTOMOUNT flag needs to be set on the
>dentry in ->d_revalidate().
>
>The false return from cifs_d_revalidate(), due to the inode now
>being marked with the S_AUTOMOUNT flag might not invalidate the
>dentry if there is a concurrent path walk. This is because the
>dentry reference count will be at least 2 in this case causing
>d_invalidate() to return EBUSY. So the asumption that the dentry
>will be discarded then correctly instantiated via ->lookup() might
>not hold.
>
>Signed-off-by: Ian Kent <ikent@redhat.com>
>---
>
> fs/cifs/dir.c |   17 ++++++++++++-----
> 1 files changed, 12 insertions(+), 5 deletions(-)
>
>
>diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
>index 2b76e28..f00cfd2 100644
>--- a/fs/cifs/dir.c
>+++ b/fs/cifs/dir.c
>@@ -682,12 +682,19 @@ cifs_d_revalidate(struct dentry *direntry, struct nameidata *nd)
> 			return 0;
> 		else {
> 			/*
>-			 * Forcibly invalidate automounting directory inodes
>-			 * (remote DFS directories) so to have them
>-			 * instantiated again for automount
>+			 * If the inode wasn't known to be a dfs entry when
>+			 * the dentry was instantiated, such as when created
>+			 * via ->readdir(), it needs to be set now since the
>+			 * attributes will have been updated by
>+			 * cifs_revalidate_dentry().
> 			 */
>-			if (IS_AUTOMOUNT(direntry->d_inode))
>-				return 0;
>+			if (IS_AUTOMOUNT(direntry->d_inode) &&
>+			   !(direntry->d_flags & DCACHE_NEED_AUTOMOUNT)) {
>+				spin_lock(&direntry->d_lock);
>+				direntry->d_flags |= DCACHE_NEED_AUTOMOUNT;
>+				spin_unlock(&direntry->d_lock);
>+			}
>+
> 			return 1;
> 		}
> 	}

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Attachments on bug 786149: 567951 | 567961 | 567962 | 568665 | 568666 | 577804 | 580327 | 580329 | 581138