From f1e67e355c2aafeddf1eac31335709236996d2fe Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 18 Nov 2019 14:28:24 +0100 Subject: fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t Bit spinlocks are problematic if PREEMPT_RT is enabled, because they disable preemption, which is undesired for latency reasons and breaks when regular spinlocks are taken within the bit_spinlock locked region because regular spinlocks are converted to 'sleeping spinlocks' on RT. PREEMPT_RT replaced the bit spinlocks with regular spinlocks to avoid this problem. The replacement was done conditionaly at compile time, but Christoph requested to do an unconditional conversion. Jan suggested to move the spinlock into a existing padding hole which avoids a size increase of struct buffer_head on production kernels. As a benefit the lock gains lockdep coverage. [ bigeasy: Remove the wrapper and use always spinlock_t and move it into the padding hole ] Signed-off-by: Thomas Gleixner Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Reviewed-by: Jan Kara Cc: Christoph Hellwig Link: https://lkml.kernel.org/r/20191118132824.rclhrbujqh4b4g4d@linutronix.de --- fs/ext4/page-io.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'fs/ext4/page-io.c') diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index 68b39e75446a..de6fe969f773 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -125,11 +125,10 @@ static void ext4_finish_bio(struct bio *bio) } bh = head = page_buffers(page); /* - * We check all buffers in the page under BH_Uptodate_Lock + * We check all buffers in the page under b_uptodate_lock * to avoid races with other end io clearing async_write flags */ - local_irq_save(flags); - bit_spin_lock(BH_Uptodate_Lock, &head->b_state); + spin_lock_irqsave(&head->b_uptodate_lock, flags); do { if (bh_offset(bh) < bio_start || bh_offset(bh) + bh->b_size > bio_end) { @@ -141,8 +140,7 @@ static void ext4_finish_bio(struct bio *bio) if (bio->bi_status) buffer_io_error(bh); } while ((bh = bh->b_this_page) != head); - bit_spin_unlock(BH_Uptodate_Lock, &head->b_state); - local_irq_restore(flags); + spin_unlock_irqrestore(&head->b_uptodate_lock, flags); if (!under_io) { fscrypt_free_bounce_page(bounce_page); end_page_writeback(page); -- cgit v1.2.3-58-ga151