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From: Thomas Gleixner <tglx@linutronix.de>
Date: Fri, 9 Aug 2019 14:42:27 +0200
Subject: [PATCH 1/7] jbd2: Simplify journal_unmap_buffer()
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.4/older/patches-5.4.17-rt8.tar.xz
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>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: linux-ext4@vger.kernel.org
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
fs/jbd2/transaction.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -2199,7 +2199,8 @@ 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 */
@@ -2207,10 +2208,6 @@ 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)
@@ -2332,7 +2329,6 @@ 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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