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[174.109.170.245]) by smtp.gmail.com with ESMTPSA id y12-20020ac8704c000000b003b6302f2580sm4098202qtm.22.2023.01.25.13.51.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Jan 2023 13:51:17 -0800 (PST) Date: Wed, 25 Jan 2023 16:51:16 -0500 From: Josef Bacik To: Christoph Hellwig Cc: Chris Mason , David Sterba , Damien Le Moal , Naohiro Aota , Johannes Thumshirn , Qu Wenruo , Jens Axboe , "Darrick J. Wong" , linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 23/34] btrfs: allow btrfs_submit_bio to split bios Message-ID: References: <20230121065031.1139353-1-hch@lst.de> <20230121065031.1139353-24-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230121065031.1139353-24-hch@lst.de> Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Sat, Jan 21, 2023 at 07:50:20AM +0100, Christoph Hellwig wrote: > Currently the I/O submitters have to split bios according to the > chunk stripe boundaries. This leads to extra lookups in the extent > trees and a lot of boilerplate code. > > To drop this requirement, split the bio when __btrfs_map_block > returns a mapping that is smaller than the requested size and > keep a count of pending bios in the original btrfs_bio so that > the upper level completion is only invoked when all clones have > completed. > > Based on a patch from Qu Wenruo. > > Signed-off-by: Christoph Hellwig > Reviewed-by: Josef Bacik > Reviewed-by: Johannes Thumshirn > Reviewed-by: Qu Wenruo > --- > fs/btrfs/bio.c | 108 ++++++++++++++++++++++++++++++++++++++++--------- > fs/btrfs/bio.h | 1 + > 2 files changed, 91 insertions(+), 18 deletions(-) > > diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c > index c7522ac7e0e71c..ff42b783902140 100644 > --- a/fs/btrfs/bio.c > +++ b/fs/btrfs/bio.c > @@ -17,6 +17,7 @@ > #include "file-item.h" > > static struct bio_set btrfs_bioset; > +static struct bio_set btrfs_clone_bioset; > static struct bio_set btrfs_repair_bioset; > static mempool_t btrfs_failed_bio_pool; > > @@ -38,6 +39,7 @@ static inline void btrfs_bio_init(struct btrfs_bio *bbio, > bbio->inode = inode; > bbio->end_io = end_io; > bbio->private = private; > + atomic_set(&bbio->pending_ios, 1); > } > > /* > @@ -75,6 +77,58 @@ struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size, > return bio; > } > > +static struct bio *btrfs_split_bio(struct bio *orig, u64 map_length) > +{ > + struct btrfs_bio *orig_bbio = btrfs_bio(orig); > + struct bio *bio; > + > + bio = bio_split(orig, map_length >> SECTOR_SHIFT, GFP_NOFS, > + &btrfs_clone_bioset); > + btrfs_bio_init(btrfs_bio(bio), orig_bbio->inode, NULL, orig_bbio); > + > + btrfs_bio(bio)->file_offset = orig_bbio->file_offset; > + if (!(orig->bi_opf & REQ_BTRFS_ONE_ORDERED)) > + orig_bbio->file_offset += map_length; > + > + atomic_inc(&orig_bbio->pending_ios); > + return bio; > +} > + > +static void btrfs_orig_write_end_io(struct bio *bio); > +static void btrfs_bbio_propagate_error(struct btrfs_bio *bbio, > + struct btrfs_bio *orig_bbio) > +{ > + /* > + * For writes btrfs tolerates nr_mirrors - 1 write failures, so we > + * can't just blindly propagate a write failure here. > + * Instead increment the error count in the original I/O context so > + * that it is guaranteed to be larger than the error tolerance. > + */ > + if (bbio->bio.bi_end_io == &btrfs_orig_write_end_io) { > + struct btrfs_io_stripe *orig_stripe = orig_bbio->bio.bi_private; > + struct btrfs_io_context *orig_bioc = orig_stripe->bioc; > + > + atomic_add(orig_bioc->max_errors, &orig_bioc->error); > + } else { > + orig_bbio->bio.bi_status = bbio->bio.bi_status; > + } > +} > + > +static void btrfs_orig_bbio_end_io(struct btrfs_bio *bbio) > +{ > + if (bbio->bio.bi_pool == &btrfs_clone_bioset) { > + struct btrfs_bio *orig_bbio = bbio->private; > + > + if (bbio->bio.bi_status) > + btrfs_bbio_propagate_error(bbio, orig_bbio); > + bio_put(&bbio->bio); > + bbio = orig_bbio; > + } > + > + if (atomic_dec_and_test(&bbio->pending_ios)) > + bbio->end_io(bbio); > +} > + > static int next_repair_mirror(struct btrfs_failed_bio *fbio, int cur_mirror) > { > if (cur_mirror == fbio->num_copies) > @@ -92,7 +146,7 @@ static int prev_repair_mirror(struct btrfs_failed_bio *fbio, int cur_mirror) > static void btrfs_repair_done(struct btrfs_failed_bio *fbio) > { > if (atomic_dec_and_test(&fbio->repair_count)) { > - fbio->bbio->end_io(fbio->bbio); > + btrfs_orig_bbio_end_io(fbio->bbio); > mempool_free(fbio, &btrfs_failed_bio_pool); > } > } > @@ -232,7 +286,7 @@ static void btrfs_check_read_bio(struct btrfs_bio *bbio, > if (unlikely(fbio)) > btrfs_repair_done(fbio); > else > - bbio->end_io(bbio); > + btrfs_orig_bbio_end_io(bbio); > } > > static void btrfs_log_dev_io_error(struct bio *bio, struct btrfs_device *dev) > @@ -286,7 +340,7 @@ static void btrfs_simple_end_io(struct bio *bio) > } else { > if (bio_op(bio) == REQ_OP_ZONE_APPEND) > btrfs_record_physical_zoned(bbio); > - bbio->end_io(bbio); > + btrfs_orig_bbio_end_io(bbio); > } > } > > @@ -300,7 +354,7 @@ static void btrfs_raid56_end_io(struct bio *bio) > if (bio_op(bio) == REQ_OP_READ && !(bbio->bio.bi_opf & REQ_META)) > btrfs_check_read_bio(bbio, NULL); > else > - bbio->end_io(bbio); > + btrfs_orig_bbio_end_io(bbio); > > btrfs_put_bioc(bioc); > } > @@ -327,7 +381,7 @@ static void btrfs_orig_write_end_io(struct bio *bio) > else > bio->bi_status = BLK_STS_OK; > > - bbio->end_io(bbio); > + btrfs_orig_bbio_end_io(bbio); > btrfs_put_bioc(bioc); > } > > @@ -492,7 +546,7 @@ static void run_one_async_done(struct btrfs_work *work) > > /* If an error occurred we just want to clean up the bio and move on */ > if (bio->bi_status) { > - btrfs_bio_end_io(async->bbio, bio->bi_status); > + btrfs_orig_bbio_end_io(async->bbio); > return; > } > > @@ -567,8 +621,8 @@ static bool btrfs_wq_submit_bio(struct btrfs_bio *bbio, > return true; > } > > -void btrfs_submit_bio(struct btrfs_fs_info *fs_info, struct bio *bio, > - int mirror_num) > +static bool btrfs_submit_chunk(struct btrfs_fs_info *fs_info, struct bio *bio, > + int mirror_num) > { > struct btrfs_bio *bbio = btrfs_bio(bio); > u64 logical = bio->bi_iter.bi_sector << 9; > @@ -587,11 +641,10 @@ void btrfs_submit_bio(struct btrfs_fs_info *fs_info, struct bio *bio, > goto fail; > } > > + map_length = min(map_length, length); > if (map_length < length) { > - btrfs_crit(fs_info, > - "mapping failed logical %llu bio len %llu len %llu", > - logical, length, map_length); > - BUG(); > + bio = btrfs_split_bio(bio, map_length); > + bbio = btrfs_bio(bio); > } > > /* > @@ -602,14 +655,14 @@ void btrfs_submit_bio(struct btrfs_fs_info *fs_info, struct bio *bio, > bbio->saved_iter = bio->bi_iter; > ret = btrfs_lookup_bio_sums(bbio); > if (ret) > - goto fail; > + goto fail_put_bio; > } > > if (btrfs_op(bio) == BTRFS_MAP_WRITE) { > if (bio_op(bio) == REQ_OP_ZONE_APPEND) { > ret = btrfs_extract_ordered_extent(btrfs_bio(bio)); > if (ret) > - goto fail; > + goto fail_put_bio; > } > > /* > @@ -621,20 +674,33 @@ void btrfs_submit_bio(struct btrfs_fs_info *fs_info, struct bio *bio, > !btrfs_is_data_reloc_root(bbio->inode->root)) { > if (should_async_write(bbio) && > btrfs_wq_submit_bio(bbio, bioc, &smap, mirror_num)) > - return; > + goto done; > > ret = btrfs_bio_csum(bbio); > if (ret) > - goto fail; > + goto fail_put_bio; > } > } > > __btrfs_submit_bio(bio, bioc, &smap, mirror_num); > - return; > +done: > + return map_length == length; > > +fail_put_bio: > + if (map_length < length) > + bio_put(bio); This is causing a panic in btrfs/125 because you set bbio to btrfs_bio(split_bio), which has a NULL end_io. You need something like the following so that we're ending the correct bbio. Thanks, Josef diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c index 5d4b67fc44f4..f3a357c48e69 100644 --- a/fs/btrfs/bio.c +++ b/fs/btrfs/bio.c @@ -607,6 +607,7 @@ static bool btrfs_submit_chunk(struct btrfs_fs_info *fs_info, struct bio *bio, int mirror_num) { struct btrfs_bio *bbio = btrfs_bio(bio); + struct btrfs_bio *orig_bbio = bbio; u64 logical = bio->bi_iter.bi_sector << 9; u64 length = bio->bi_iter.bi_size; u64 map_length = length; @@ -673,7 +674,7 @@ static bool btrfs_submit_chunk(struct btrfs_fs_info *fs_info, struct bio *bio, bio_put(bio); fail: btrfs_bio_counter_dec(fs_info); - btrfs_bio_end_io(bbio, ret); + btrfs_bio_end_io(orig_bbio, ret); /* Do not submit another chunk */ return true; }