From: Qu Wenruo Date: Thu, 23 Oct 2025 04:49:16 +0000 (+1030) Subject: btrfs: make sure all btrfs_bio::end_io are called in task context X-Git-Tag: v6.19-rc1~167^2~61 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4591c3ef751d861d7dd95ff4d2aadb1b5e95854e;p=thirdparty%2Fkernel%2Flinux.git btrfs: make sure all btrfs_bio::end_io are called in task context [BACKGROUND] Btrfs has a lot of different bi_end_io functions, to handle different raid profiles. But they introduced a lot of different contexts for btrfs_bio::end_io() calls: - Simple read bios Run in task context, backed by either endio_meta_workers or endio_workers. - Simple write bios Run in IRQ context. - RAID56 write or rebuild bios Run in task context, backed by rmw_workers. - Mirrored write bios Run in irq context. This is inconsistent, and contributes to the number of workqueues used in btrfs. [ENHANCEMENT] Make all the above bios call their btrfs_bio::end_io() in task context, backed by either endio_meta_workers for metadata, or endio_workers for data. For simple write bios, merge the handling into simple_end_io_work(). For mirrored write bios, it will be a little more complex, since both the original or the cloned bios can run the final btrfs_bio::end_io(). Here we make sure the cloned bios are using btrfs_bioset, to reuse the end_io_work, and run both original and cloned work inside the workqueue. Add extra ASSERT()s to make sure btrfs_bio_end_io() is running in task context. This not only unifies the context for btrfs_bio::end_io() functions, but also opens a new door for further btrfs_bio::end_io() related cleanups. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c index b85b6b21b5450..52b8893f26f16 100644 --- a/fs/btrfs/bio.c +++ b/fs/btrfs/bio.c @@ -102,6 +102,9 @@ static struct btrfs_bio *btrfs_split_bio(struct btrfs_fs_info *fs_info, void btrfs_bio_end_io(struct btrfs_bio *bbio, blk_status_t status) { + /* Make sure we're already in task context. */ + ASSERT(in_task()); + bbio->bio.bi_status = status; if (bbio->bio.bi_pool == &btrfs_clone_bioset) { struct btrfs_bio *orig_bbio = bbio->private; @@ -318,15 +321,20 @@ static struct workqueue_struct *btrfs_end_io_wq(const struct btrfs_fs_info *fs_i return fs_info->endio_workers; } -static void btrfs_end_bio_work(struct work_struct *work) +static void simple_end_io_work(struct work_struct *work) { struct btrfs_bio *bbio = container_of(work, struct btrfs_bio, end_io_work); + struct bio *bio = &bbio->bio; - /* Metadata reads are checked and repaired by the submitter. */ - if (is_data_bbio(bbio)) - btrfs_check_read_bio(bbio, bbio->bio.bi_private); - else - btrfs_bio_end_io(bbio, bbio->bio.bi_status); + if (bio_op(bio) == REQ_OP_READ) { + /* Metadata reads are checked and repaired by the submitter. */ + if (is_data_bbio(bbio)) + return btrfs_check_read_bio(bbio, bbio->bio.bi_private); + return btrfs_bio_end_io(bbio, bbio->bio.bi_status); + } + if (bio_is_zone_append(bio) && !bio->bi_status) + btrfs_record_physical_zoned(bbio); + btrfs_bio_end_io(bbio, bbio->bio.bi_status); } static void btrfs_simple_end_io(struct bio *bio) @@ -340,14 +348,8 @@ static void btrfs_simple_end_io(struct bio *bio) if (bio->bi_status) btrfs_log_dev_io_error(bio, dev); - if (bio_op(bio) == REQ_OP_READ) { - INIT_WORK(&bbio->end_io_work, btrfs_end_bio_work); - queue_work(btrfs_end_io_wq(fs_info, bio), &bbio->end_io_work); - } else { - if (bio_is_zone_append(bio) && !bio->bi_status) - btrfs_record_physical_zoned(bbio); - btrfs_bio_end_io(bbio, bbio->bio.bi_status); - } + INIT_WORK(&bbio->end_io_work, simple_end_io_work); + queue_work(btrfs_end_io_wq(fs_info, bio), &bbio->end_io_work); } static void btrfs_raid56_end_io(struct bio *bio) @@ -355,6 +357,9 @@ static void btrfs_raid56_end_io(struct bio *bio) struct btrfs_io_context *bioc = bio->bi_private; struct btrfs_bio *bbio = btrfs_bio(bio); + /* RAID56 endio is always handled in workqueue. */ + ASSERT(in_task()); + btrfs_bio_counter_dec(bioc->fs_info); bbio->mirror_num = bioc->mirror_num; if (bio_op(bio) == REQ_OP_READ && is_data_bbio(bbio)) @@ -365,11 +370,12 @@ static void btrfs_raid56_end_io(struct bio *bio) btrfs_put_bioc(bioc); } -static void btrfs_orig_write_end_io(struct bio *bio) +static void orig_write_end_io_work(struct work_struct *work) { + struct btrfs_bio *bbio = container_of(work, struct btrfs_bio, end_io_work); + struct bio *bio = &bbio->bio; struct btrfs_io_stripe *stripe = bio->bi_private; struct btrfs_io_context *bioc = stripe->bioc; - struct btrfs_bio *bbio = btrfs_bio(bio); btrfs_bio_counter_dec(bioc->fs_info); @@ -394,8 +400,18 @@ static void btrfs_orig_write_end_io(struct bio *bio) btrfs_put_bioc(bioc); } -static void btrfs_clone_write_end_io(struct bio *bio) +static void btrfs_orig_write_end_io(struct bio *bio) +{ + struct btrfs_bio *bbio = btrfs_bio(bio); + + INIT_WORK(&bbio->end_io_work, orig_write_end_io_work); + queue_work(btrfs_end_io_wq(bbio->inode->root->fs_info, bio), &bbio->end_io_work); +} + +static void clone_write_end_io_work(struct work_struct *work) { + struct btrfs_bio *bbio = container_of(work, struct btrfs_bio, end_io_work); + struct bio *bio = &bbio->bio; struct btrfs_io_stripe *stripe = bio->bi_private; if (bio->bi_status) { @@ -410,6 +426,14 @@ static void btrfs_clone_write_end_io(struct bio *bio) bio_put(bio); } +static void btrfs_clone_write_end_io(struct bio *bio) +{ + struct btrfs_bio *bbio = btrfs_bio(bio); + + INIT_WORK(&bbio->end_io_work, clone_write_end_io_work); + queue_work(btrfs_end_io_wq(bbio->inode->root->fs_info, bio), &bbio->end_io_work); +} + static void btrfs_submit_dev_bio(struct btrfs_device *dev, struct bio *bio) { if (!dev || !dev->bdev || @@ -456,6 +480,7 @@ static void btrfs_submit_dev_bio(struct btrfs_device *dev, struct bio *bio) static void btrfs_submit_mirrored_bio(struct btrfs_io_context *bioc, int dev_nr) { struct bio *orig_bio = bioc->orig_bio, *bio; + struct btrfs_bio *orig_bbio = btrfs_bio(orig_bio); ASSERT(bio_op(orig_bio) != REQ_OP_READ); @@ -464,8 +489,11 @@ static void btrfs_submit_mirrored_bio(struct btrfs_io_context *bioc, int dev_nr) bio = orig_bio; bio->bi_end_io = btrfs_orig_write_end_io; } else { - bio = bio_alloc_clone(NULL, orig_bio, GFP_NOFS, &fs_bio_set); + /* We need to use endio_work to run end_io in task context. */ + bio = bio_alloc_clone(NULL, orig_bio, GFP_NOFS, &btrfs_bioset); bio_inc_remaining(orig_bio); + btrfs_bio_init(btrfs_bio(bio), orig_bbio->inode, + orig_bbio->file_offset, NULL, NULL); bio->bi_end_io = btrfs_clone_write_end_io; }