2007-01-23 17:23:43

by Eric Sandeen

[permalink] [raw]
Subject: [PATCH] [RESEND] return ENOENT from ext3_link when racing with unlink

(resend now that LCA is done)

An update from the earlier thread,
[PATCH] [RFC] remove ext3 inode from orphan list when link and unlink race

I think this is better than the original idea of trying to handle the race;
I've seen that the orphan inode list can get corrupted, but there may well
be other implications of the race which haven't yet been exposed. I think
it's safer to simply return -ENOENT in this race window, and avoid other
potential problems. Anything wrong with this?

Thanks for the comments suggesting this approach in the prior thread.




Return -ENOENT from ext[34]_link if we've raced with unlink and
i_nlink is 0. Doing otherwise has the potential to corrupt the
orphan inode list, because we'd wind up with an inode with a
non-zero link count on the list, and it will never get properly
cleaned up & removed from the orphan list before it is freed.

Signed-off-by: Eric Sandeen <[email protected]>

Index: linux-2.6.19/fs/ext3/namei.c
--- linux-2.6.19.orig/fs/ext3/namei.c
+++ linux-2.6.19/fs/ext3/namei.c
@@ -2191,6 +2191,8 @@ static int ext3_link (struct dentry * ol

if (inode->i_nlink >= EXT3_LINK_MAX)
return -EMLINK;
+ if (inode->i_nlink == 0)
+ return -ENOENT;

handle = ext3_journal_start(dir, EXT3_DATA_TRANS_BLOCKS(dir->i_sb) +
Index: linux-2.6.19/fs/ext4/namei.c
--- linux-2.6.19.orig/fs/ext4/namei.c
+++ linux-2.6.19/fs/ext4/namei.c
@@ -2189,6 +2189,8 @@ static int ext4_link (struct dentry * ol

if (inode->i_nlink >= EXT4_LINK_MAX)
return -EMLINK;
+ if (inode->i_nlink == 0)
+ return -ENOENT;

handle = ext4_journal_start(dir, EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +