[83/90] ext4: Properly count journal credits for long symlinks

[Greg KH]

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

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

From: Eric Sandeen <sandeen@xxxxxxxxxx>

commit 8c20871998c082f6fbc963f1449a5ba5140ee39a upstream.

Commit df5e6223407e ("ext4: fix deadlock in ext4_symlink() in ENOSPC
conditions") 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
jbd2_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@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Acked-by: "Theodore Ts'o" <tytso@xxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 fs/ext4/namei.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2264,9 +2264,11 @@ static int ext4_symlink(struct inode *di
 		/*
 		 * 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 + EXT4_MAXQUOTAS_INIT_BLOCKS(dir->i_sb);
+		credits = 4 + EXT4_MAXQUOTAS_INIT_BLOCKS(dir->i_sb) +
+			  EXT4_XATTR_TRANS_BLOCKS;
 	} else {
 		/*
 		 * Fast symlink. We have to add entry to directory


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