| Message ID | 20230121065031.1139353-4-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/34] block: export bio_split_rw | expand |
On 21/01/2023 14:50, Christoph Hellwig wrote: > All btrfs_bio I/Os are associated with an inode. Add a pointer to that > inode, which will allow to simplify a lot of calling conventions, and > which will be needed in the I/O completion path in the future. > > This grow the btrfs_bio struture by a pointer, but that grows will Nit: s/struture/structure > be offset by the removal of the device pointer soon. > > Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Anand Jain <anand.jain@oracle.com>
On 21.01.23 07:50, Christoph Hellwig wrote: > This grow the btrfs_bio struture by a pointer, but that grows will s/struture/structure Otherwise looks good, Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Looks good,
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
On 2023/1/21 14:50, Christoph Hellwig wrote: > All btrfs_bio I/Os are associated with an inode. Add a pointer to that > inode, which will allow to simplify a lot of calling conventions, and > which will be needed in the I/O completion path in the future. > > This grow the btrfs_bio struture by a pointer, but that grows will > be offset by the removal of the device pointer soon. > > Signed-off-by: Christoph Hellwig <hch@lst.de> With my recent restart on scrub rework, this patch makes me wonder, what if scrub wants to use btrfs_bio, but don't want to pass a valid btrfs_inode pointer? E.g. scrub code just wants to read certain mirror of a logical bytenr. This can simplify the handling of RAID56, as for data stripes the repair path is the same, just try the next mirror(s). Furthermore most of the new btrfs_bio code is handling data reads by triggering read-repair automatically. This can be unnecessary for scrub. For now, I can workaround the behavior by setting REQ_META and pass btree_inode as the inode, but this is only a workaround. This can be problematic especially if we want to merge metadata and data verification behavior. Any better ideas on this? And since we're here, can we also have btrfs equivalent of on-stack bio? As scrub can benefit a lot from that, as for sector-by-sector read, we want to avoid repeating allocating/freeing a btrfs_bio just for reading one sector. (The existing behavior is using on-stack bio with bio_init/bio_uninit inside scrub_recheck_block()) Thanks, Qu > --- > fs/btrfs/bio.c | 8 ++++++-- > fs/btrfs/bio.h | 5 ++++- > fs/btrfs/compression.c | 3 ++- > fs/btrfs/extent_io.c | 8 ++++---- > fs/btrfs/inode.c | 4 +++- > 5 files changed, 19 insertions(+), 9 deletions(-) > > diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c > index 8affc88b0e0a4b..2398bb263957b2 100644 > --- a/fs/btrfs/bio.c > +++ b/fs/btrfs/bio.c > @@ -22,9 +22,11 @@ static struct bio_set btrfs_bioset; > * is already initialized by the block layer. > */ > static inline void btrfs_bio_init(struct btrfs_bio *bbio, > + struct btrfs_inode *inode, > btrfs_bio_end_io_t end_io, void *private) > { > memset(bbio, 0, offsetof(struct btrfs_bio, bio)); > + bbio->inode = inode; > bbio->end_io = end_io; > bbio->private = private; > } > @@ -37,16 +39,18 @@ static inline void btrfs_bio_init(struct btrfs_bio *bbio, > * a mempool. > */ > struct bio *btrfs_bio_alloc(unsigned int nr_vecs, blk_opf_t opf, > + struct btrfs_inode *inode, > btrfs_bio_end_io_t end_io, void *private) > { > struct bio *bio; > > bio = bio_alloc_bioset(NULL, nr_vecs, opf, GFP_NOFS, &btrfs_bioset); > - btrfs_bio_init(btrfs_bio(bio), end_io, private); > + btrfs_bio_init(btrfs_bio(bio), inode, end_io, private); > return bio; > } > > struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size, > + struct btrfs_inode *inode, > btrfs_bio_end_io_t end_io, void *private) > { > struct bio *bio; > @@ -56,7 +60,7 @@ struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size, > > bio = bio_alloc_clone(orig->bi_bdev, orig, GFP_NOFS, &btrfs_bioset); > bbio = btrfs_bio(bio); > - btrfs_bio_init(bbio, end_io, private); > + btrfs_bio_init(bbio, inode, end_io, private); > > bio_trim(bio, offset >> 9, size >> 9); > bbio->iter = bio->bi_iter; > diff --git a/fs/btrfs/bio.h b/fs/btrfs/bio.h > index baaa27961cc812..8d69d0b226d99b 100644 > --- a/fs/btrfs/bio.h > +++ b/fs/btrfs/bio.h > @@ -41,7 +41,8 @@ struct btrfs_bio { > unsigned int is_metadata:1; > struct bvec_iter iter; > > - /* File offset that this I/O operates on. */ > + /* Inode and offset into it that this I/O operates on. */ > + struct btrfs_inode *inode; > u64 file_offset; > > /* @device is for stripe IO submission. */ > @@ -80,8 +81,10 @@ int __init btrfs_bioset_init(void); > void __cold btrfs_bioset_exit(void); > > struct bio *btrfs_bio_alloc(unsigned int nr_vecs, blk_opf_t opf, > + struct btrfs_inode *inode, > btrfs_bio_end_io_t end_io, void *private); > struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size, > + struct btrfs_inode *inode, > btrfs_bio_end_io_t end_io, void *private); > > > diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c > index 4a5aeb8dd4793a..b8e3e899974b34 100644 > --- a/fs/btrfs/compression.c > +++ b/fs/btrfs/compression.c > @@ -344,7 +344,8 @@ static struct bio *alloc_compressed_bio(struct compressed_bio *cb, u64 disk_byte > struct bio *bio; > int ret; > > - bio = btrfs_bio_alloc(BIO_MAX_VECS, opf, endio_func, cb); > + bio = btrfs_bio_alloc(BIO_MAX_VECS, opf, BTRFS_I(cb->inode), endio_func, > + cb); > bio->bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT; > > em = btrfs_get_chunk_map(fs_info, disk_bytenr, fs_info->sectorsize); > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index 9bd32daa9b9a6f..faf9312a46c0e1 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -740,7 +740,8 @@ int btrfs_repair_one_sector(struct btrfs_inode *inode, struct btrfs_bio *failed_ > return -EIO; > } > > - repair_bio = btrfs_bio_alloc(1, REQ_OP_READ, failed_bbio->end_io, > + repair_bio = btrfs_bio_alloc(1, REQ_OP_READ, failed_bbio->inode, > + failed_bbio->end_io, > failed_bbio->private); > repair_bbio = btrfs_bio(repair_bio); > repair_bbio->file_offset = start; > @@ -1394,9 +1395,8 @@ static int alloc_new_bio(struct btrfs_inode *inode, > struct bio *bio; > int ret; > > - ASSERT(bio_ctrl->end_io_func); > - > - bio = btrfs_bio_alloc(BIO_MAX_VECS, opf, bio_ctrl->end_io_func, NULL); > + bio = btrfs_bio_alloc(BIO_MAX_VECS, opf, inode, bio_ctrl->end_io_func, > + NULL); > /* > * For compressed page range, its disk_bytenr is always @disk_bytenr > * passed in, no matter if we have added any range into previous bio. > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 3c49742f0d4556..0a85e42f114cc5 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -8097,7 +8097,8 @@ static void btrfs_submit_direct(const struct iomap_iter *iter, > * the allocation is backed by btrfs_bioset. > */ > bio = btrfs_bio_clone_partial(dio_bio, clone_offset, clone_len, > - btrfs_end_dio_bio, dip); > + BTRFS_I(inode), btrfs_end_dio_bio, > + dip); > btrfs_bio(bio)->file_offset = file_offset; > > if (bio_op(bio) == REQ_OP_ZONE_APPEND) { > @@ -10409,6 +10410,7 @@ int btrfs_encoded_read_regular_fill_pages(struct btrfs_inode *inode, > > if (!bio) { > bio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, > + inode, > btrfs_encoded_read_endio, > &priv); > bio->bi_iter.bi_sector =
On Tue, Mar 07, 2023 at 09:44:32AM +0800, Qu Wenruo wrote: > With my recent restart on scrub rework, this patch makes me wonder, what if > scrub wants to use btrfs_bio, but don't want to pass a valid btrfs_inode > pointer? The full inode is only really needed for the data repair code. But a lot of code uses the fs_info, which would have to be added as a separate counter. The other usage is the sync_writers counter, which is a bit odd and should probably be keyed off the REQ_SYNC flag instead. > E.g. scrub code just wants to read certain mirror of a logical bytenr. > This can simplify the handling of RAID56, as for data stripes the repair > path is the same, just try the next mirror(s). > > Furthermore most of the new btrfs_bio code is handling data reads by > triggering read-repair automatically. > This can be unnecessary for scrub. This sounds like you don't want to use the btrfs_bio at all as you don't rely on any of the functionality from it. > > And since we're here, can we also have btrfs equivalent of on-stack bio? > As scrub can benefit a lot from that, as for sector-by-sector read, we want > to avoid repeating allocating/freeing a btrfs_bio just for reading one > sector. > (The existing behavior is using on-stack bio with bio_init/bio_uninit > inside scrub_recheck_block()) You can do that right now by declaring a btrfs_bio on-stack and then calling bio_init on the embedded bio followed by a btrfs_bio_init on the btrfs_bio. But I don't think doing this will actually be a win for the scrub code in terms of speed or code size.
On 2023/3/7 22:41, Christoph Hellwig wrote: > On Tue, Mar 07, 2023 at 09:44:32AM +0800, Qu Wenruo wrote: >> With my recent restart on scrub rework, this patch makes me wonder, what if >> scrub wants to use btrfs_bio, but don't want to pass a valid btrfs_inode >> pointer? > > The full inode is only really needed for the data repair code. But a lot > of code uses the fs_info, which would have to be added as a separate > counter. The other usage is the sync_writers counter, which is a bit > odd and should probably be keyed off the REQ_SYNC flag instead. > >> E.g. scrub code just wants to read certain mirror of a logical bytenr. >> This can simplify the handling of RAID56, as for data stripes the repair >> path is the same, just try the next mirror(s). >> >> Furthermore most of the new btrfs_bio code is handling data reads by >> triggering read-repair automatically. >> This can be unnecessary for scrub. > > This sounds like you don't want to use the btrfs_bio at all as you > don't rely on any of the functionality from it. Well, to me the proper mirror_num based read is the core of btrfs_bio, not the read-repair thing. Thus I'm not that convinced fully automatic read-repair integrated into btrfs_bio is a good idea. Thanks, Qu > >> >> And since we're here, can we also have btrfs equivalent of on-stack bio? >> As scrub can benefit a lot from that, as for sector-by-sector read, we want >> to avoid repeating allocating/freeing a btrfs_bio just for reading one >> sector. >> (The existing behavior is using on-stack bio with bio_init/bio_uninit >> inside scrub_recheck_block()) > > You can do that right now by declaring a btrfs_bio on-stack and then > calling bio_init on the embedded bio followed by a btrfs_bio_init on > the btrfs_bio. But I don't think doing this will actually be a win > for the scrub code in terms of speed or code size.
On 2023/3/8 06:21, Qu Wenruo wrote: > > > On 2023/3/7 22:41, Christoph Hellwig wrote: >> On Tue, Mar 07, 2023 at 09:44:32AM +0800, Qu Wenruo wrote: >>> With my recent restart on scrub rework, this patch makes me wonder, >>> what if >>> scrub wants to use btrfs_bio, but don't want to pass a valid btrfs_inode >>> pointer? >> >> The full inode is only really needed for the data repair code. But a lot >> of code uses the fs_info, which would have to be added as a separate >> counter. The other usage is the sync_writers counter, which is a bit >> odd and should probably be keyed off the REQ_SYNC flag instead. >> >>> E.g. scrub code just wants to read certain mirror of a logical bytenr. >>> This can simplify the handling of RAID56, as for data stripes the repair >>> path is the same, just try the next mirror(s). >>> >>> Furthermore most of the new btrfs_bio code is handling data reads by >>> triggering read-repair automatically. >>> This can be unnecessary for scrub. >> >> This sounds like you don't want to use the btrfs_bio at all as you >> don't rely on any of the functionality from it. > > Well, to me the proper mirror_num based read is the core of btrfs_bio, > not the read-repair thing. > > Thus I'm not that convinced fully automatic read-repair integrated into > btrfs_bio is a good idea. BTW, I also checked if I can craft a scrub specific version of btrfs_submit_bio(). The result doesn't look good at all. Without a btrfs_bio structure, it's already pretty hard to properly put bioc, decrease the bio counter. Or I need to create a scrub_bio, and re-implement all the needed endio function handling. So please really consider the simplest case, one just wants to read/write some data using logical + mirror_num, without any btrfs inode nor csum verification. Thanks, Qu > > Thanks, > Qu >> >>> >>> And since we're here, can we also have btrfs equivalent of on-stack bio? >>> As scrub can benefit a lot from that, as for sector-by-sector read, >>> we want >>> to avoid repeating allocating/freeing a btrfs_bio just for reading one >>> sector. >>> (The existing behavior is using on-stack bio with bio_init/bio_uninit >>> inside scrub_recheck_block()) >> >> You can do that right now by declaring a btrfs_bio on-stack and then >> calling bio_init on the embedded bio followed by a btrfs_bio_init on >> the btrfs_bio. But I don't think doing this will actually be a win >> for the scrub code in terms of speed or code size.
On Wed, Mar 08, 2023 at 02:04:26PM +0800, Qu Wenruo wrote: > BTW, I also checked if I can craft a scrub specific version of > btrfs_submit_bio(). > > The result doesn't look good at all. > > Without a btrfs_bio structure, it's already pretty hard to properly put > bioc, decrease the bio counter. > > Or I need to create a scrub_bio, and re-implement all the needed endio > function handling. > > So please really consider the simplest case, one just wants to read/write > some data using logical + mirror_num, without any btrfs inode nor csum > verification. As said before with a little more work we could get away without the inode. But the above sounds a little strange to me. Can you share your current code? Maybe I can come up with some better ideas.
On 2023/3/8 22:28, Christoph Hellwig wrote: > On Wed, Mar 08, 2023 at 02:04:26PM +0800, Qu Wenruo wrote: >> BTW, I also checked if I can craft a scrub specific version of >> btrfs_submit_bio(). >> >> The result doesn't look good at all. >> >> Without a btrfs_bio structure, it's already pretty hard to properly put >> bioc, decrease the bio counter. >> >> Or I need to create a scrub_bio, and re-implement all the needed endio >> function handling. >> >> So please really consider the simplest case, one just wants to read/write >> some data using logical + mirror_num, without any btrfs inode nor csum >> verification. > > As said before with a little more work we could get away without the > inode. But the above sounds a little strange to me. Can you share > your current code? Maybe I can come up with some better ideas. My current one is a new btrfs_submit_scrub_read() helper, getting rid of features I don't need and slightly modify the endio functions to avoid any checks if no bbio->inode. AKA, most of your idea. So that would be mostly fine. But what I'm exploring is to completely get rid of btrfs_ino, using plain bio. Things like bio counter is not a big deal as the only caller is scrub/dev-replace, thus there would be no race to change dev-replace half-way. So is bioc for non-RAID56 profiles, as we only need to grab the dev/physical and can release it immediately. But for RAID56, the bioc has to live long enough for raid56 work to finish, thus has to go btrfs_raid56_end_io() and rely on the extra bbio->end_io(). I guess I have to accept the defeat and just go btrfs_bio. Thanks, Qu
On Thu, Mar 09, 2023 at 08:08:34AM +0800, Qu Wenruo wrote: > My current one is a new btrfs_submit_scrub_read() helper, getting rid of > features I don't need and slightly modify the endio functions to avoid any > checks if no bbio->inode. AKA, most of your idea. > > So that would be mostly fine. This looks mostly ok to me. I suspect in the longer run all metadata I/O might be able to use this helper as well. > But for RAID56, the bioc has to live long enough for raid56 work to finish, > thus has to go btrfs_raid56_end_io() and rely on the extra bbio->end_io(). The bioc lifetimes for RAID56 are a bit odd and one of the things I'd love to eventually look into, but іt's not very high on the priority list right now.
On 2023/3/9 17:31, Christoph Hellwig wrote: > On Thu, Mar 09, 2023 at 08:08:34AM +0800, Qu Wenruo wrote: >> My current one is a new btrfs_submit_scrub_read() helper, getting rid of >> features I don't need and slightly modify the endio functions to avoid any >> checks if no bbio->inode. AKA, most of your idea. >> >> So that would be mostly fine. > > This looks mostly ok to me. I suspect in the longer run all metadata > I/O might be able to use this helper as well. IMHO metadata would also go into the btrfs_check_read_bio(). As for now, all the info for metadata verification is already integrated into bbio, thus in the long run, the no-check path would be the exception. > >> But for RAID56, the bioc has to live long enough for raid56 work to finish, >> thus has to go btrfs_raid56_end_io() and rely on the extra bbio->end_io(). > > The bioc lifetimes for RAID56 are a bit odd and one of the things I'd > love to eventually look into, but іt's not very high on the priority list > right now. If you have some good ideas, I'm very happy to try. My current idea is to dump a bioc for btrfs_raid_bio, so btrfs_submit_bio() path can just free the bioc after usage, no need to wait. But not sure if this change would really cleanup the code, thus it would still be very low on priority. Thanks, Qu
On Thu, Mar 09, 2023 at 06:32:41PM +0800, Qu Wenruo wrote: >> This looks mostly ok to me. I suspect in the longer run all metadata >> I/O might be able to use this helper as well. > > IMHO metadata would also go into the btrfs_check_read_bio(). Why? The reason data checksum verification is down there is so that it can deal with split bios. Metadata never gets split, so it is more logical to keep the metadata verification in the extent_buffer code.
diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c index 8affc88b0e0a4b..2398bb263957b2 100644 --- a/fs/btrfs/bio.c +++ b/fs/btrfs/bio.c @@ -22,9 +22,11 @@ static struct bio_set btrfs_bioset; * is already initialized by the block layer. */ static inline void btrfs_bio_init(struct btrfs_bio *bbio, + struct btrfs_inode *inode, btrfs_bio_end_io_t end_io, void *private) { memset(bbio, 0, offsetof(struct btrfs_bio, bio)); + bbio->inode = inode; bbio->end_io = end_io; bbio->private = private; } @@ -37,16 +39,18 @@ static inline void btrfs_bio_init(struct btrfs_bio *bbio, * a mempool. */ struct bio *btrfs_bio_alloc(unsigned int nr_vecs, blk_opf_t opf, + struct btrfs_inode *inode, btrfs_bio_end_io_t end_io, void *private) { struct bio *bio; bio = bio_alloc_bioset(NULL, nr_vecs, opf, GFP_NOFS, &btrfs_bioset); - btrfs_bio_init(btrfs_bio(bio), end_io, private); + btrfs_bio_init(btrfs_bio(bio), inode, end_io, private); return bio; } struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size, + struct btrfs_inode *inode, btrfs_bio_end_io_t end_io, void *private) { struct bio *bio; @@ -56,7 +60,7 @@ struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size, bio = bio_alloc_clone(orig->bi_bdev, orig, GFP_NOFS, &btrfs_bioset); bbio = btrfs_bio(bio); - btrfs_bio_init(bbio, end_io, private); + btrfs_bio_init(bbio, inode, end_io, private); bio_trim(bio, offset >> 9, size >> 9); bbio->iter = bio->bi_iter; diff --git a/fs/btrfs/bio.h b/fs/btrfs/bio.h index baaa27961cc812..8d69d0b226d99b 100644 --- a/fs/btrfs/bio.h +++ b/fs/btrfs/bio.h @@ -41,7 +41,8 @@ struct btrfs_bio { unsigned int is_metadata:1; struct bvec_iter iter; - /* File offset that this I/O operates on. */ + /* Inode and offset into it that this I/O operates on. */ + struct btrfs_inode *inode; u64 file_offset; /* @device is for stripe IO submission. */ @@ -80,8 +81,10 @@ int __init btrfs_bioset_init(void); void __cold btrfs_bioset_exit(void); struct bio *btrfs_bio_alloc(unsigned int nr_vecs, blk_opf_t opf, + struct btrfs_inode *inode, btrfs_bio_end_io_t end_io, void *private); struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size, + struct btrfs_inode *inode, btrfs_bio_end_io_t end_io, void *private); diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index 4a5aeb8dd4793a..b8e3e899974b34 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -344,7 +344,8 @@ static struct bio *alloc_compressed_bio(struct compressed_bio *cb, u64 disk_byte struct bio *bio; int ret; - bio = btrfs_bio_alloc(BIO_MAX_VECS, opf, endio_func, cb); + bio = btrfs_bio_alloc(BIO_MAX_VECS, opf, BTRFS_I(cb->inode), endio_func, + cb); bio->bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT; em = btrfs_get_chunk_map(fs_info, disk_bytenr, fs_info->sectorsize); diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 9bd32daa9b9a6f..faf9312a46c0e1 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -740,7 +740,8 @@ int btrfs_repair_one_sector(struct btrfs_inode *inode, struct btrfs_bio *failed_ return -EIO; } - repair_bio = btrfs_bio_alloc(1, REQ_OP_READ, failed_bbio->end_io, + repair_bio = btrfs_bio_alloc(1, REQ_OP_READ, failed_bbio->inode, + failed_bbio->end_io, failed_bbio->private); repair_bbio = btrfs_bio(repair_bio); repair_bbio->file_offset = start; @@ -1394,9 +1395,8 @@ static int alloc_new_bio(struct btrfs_inode *inode, struct bio *bio; int ret; - ASSERT(bio_ctrl->end_io_func); - - bio = btrfs_bio_alloc(BIO_MAX_VECS, opf, bio_ctrl->end_io_func, NULL); + bio = btrfs_bio_alloc(BIO_MAX_VECS, opf, inode, bio_ctrl->end_io_func, + NULL); /* * For compressed page range, its disk_bytenr is always @disk_bytenr * passed in, no matter if we have added any range into previous bio. diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 3c49742f0d4556..0a85e42f114cc5 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -8097,7 +8097,8 @@ static void btrfs_submit_direct(const struct iomap_iter *iter, * the allocation is backed by btrfs_bioset. */ bio = btrfs_bio_clone_partial(dio_bio, clone_offset, clone_len, - btrfs_end_dio_bio, dip); + BTRFS_I(inode), btrfs_end_dio_bio, + dip); btrfs_bio(bio)->file_offset = file_offset; if (bio_op(bio) == REQ_OP_ZONE_APPEND) { @@ -10409,6 +10410,7 @@ int btrfs_encoded_read_regular_fill_pages(struct btrfs_inode *inode, if (!bio) { bio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, + inode, btrfs_encoded_read_endio, &priv); bio->bi_iter.bi_sector =
All btrfs_bio I/Os are associated with an inode. Add a pointer to that inode, which will allow to simplify a lot of calling conventions, and which will be needed in the I/O completion path in the future. This grow the btrfs_bio struture by a pointer, but that grows will be offset by the removal of the device pointer soon. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/btrfs/bio.c | 8 ++++++-- fs/btrfs/bio.h | 5 ++++- fs/btrfs/compression.c | 3 ++- fs/btrfs/extent_io.c | 8 ++++---- fs/btrfs/inode.c | 4 +++- 5 files changed, 19 insertions(+), 9 deletions(-)