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Subject[patch V2 5/7] fs/jbd2: Simplify journal_unmap_buffer()
journal_unmap_buffer() checks first whether the buffer head is a journal.
If so it takes locks and then invokes jbd2_journal_grab_journal_head()
followed by another check whether this is journal head buffer.

The double checking is pointless.

Replace the initial check with jbd2_journal_grab_journal_head() which
alredy checks whether the buffer head is actually a journal.

Allows also early access to the journal head pointer for the upcoming
conversion of state lock to a regular spinlock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-ext4@vger.kernel.org
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Jan Kara <jack@suse.com>
---
V2: New patch
---
fs/jbd2/transaction.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -2196,7 +2196,8 @@ static int journal_unmap_buffer(journal_
* holding the page lock. --sct
*/

- if (!buffer_jbd(bh))
+ jh = jbd2_journal_grab_journal_head(bh);
+ if (!jh)
goto zap_buffer_unlocked;

/* OK, we have data buffer in journaled mode */
@@ -2204,10 +2205,6 @@ static int journal_unmap_buffer(journal_
jbd_lock_bh_state(bh);
spin_lock(&journal->j_list_lock);

- jh = jbd2_journal_grab_journal_head(bh);
- if (!jh)
- goto zap_buffer_no_jh;
-
/*
* We cannot remove the buffer from checkpoint lists until the
* transaction adding inode to orphan list (let's call it T)
@@ -2329,7 +2326,6 @@ static int journal_unmap_buffer(journal_
*/
jh->b_modified = 0;
jbd2_journal_put_journal_head(jh);
-zap_buffer_no_jh:
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
write_unlock(&journal->j_state_lock);

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