linux-kernel - [82/90] ext3: Properly count journal credits for long symlinks

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Date:	Fri, 12 Aug 2011 14:05:07 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Eric Sandeen <sandeen@...hat.com>,
	"Theodore Tso" <tytso@....edu>
Subject: [82/90] ext3: Properly count journal credits for long symlinks

3.0-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Eric Sandeen <sandeen@...hat.com>

commit d2db60df1e7eb39cf0f378dfc4dd8813666d46ef upstream.

Commit ae54870a1dc9 ("ext3: Fix lock inversion in ext3_symlink()")
recalculated the number of credits needed for a long symlink, in the
process of splitting it into two transactions.  However, the first
credit calculation under-counted because if selinux is enabled, credits
are needed to create the selinux xattr as well.

Overrunning the reservation will result in an OOPS in
journal_dirty_metadata() due to this assert:

  J_ASSERT_JH(jh, handle->h_buffer_credits > 0);

Fix this by increasing the reservation size.

Signed-off-by: Eric Sandeen <sandeen@...hat.com>
Reviewed-by: Jan Kara <jack@...e.cz>
Acked-by: "Theodore Ts'o" <tytso@....edu>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 fs/ext3/namei.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/ext3/namei.c
+++ b/fs/ext3/namei.c
@@ -2210,9 +2210,11 @@ static int ext3_symlink (struct inode *
 		/*
 		 * For non-fast symlinks, we just allocate inode and put it on
 		 * orphan list in the first transaction => we need bitmap,
-		 * group descriptor, sb, inode block, quota blocks.
+		 * group descriptor, sb, inode block, quota blocks, and
+		 * possibly selinux xattr blocks.
 		 */
-		credits = 4 + EXT3_MAXQUOTAS_INIT_BLOCKS(dir->i_sb);
+		credits = 4 + EXT3_MAXQUOTAS_INIT_BLOCKS(dir->i_sb) +
+			  EXT3_XATTR_TRANS_BLOCKS;
 	} else {
 		/*
 		 * Fast symlink. We have to add entry to directory


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