[PATCH v2 02/17] btrfs: save bio::bi_iter into btrfs_bio::iter before any endio
From: Qu Wenruo <hidden>
Date: 2021-12-06 02:30:07
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
Currently btrfs_bio::iter is only utilized by direct IO. But later we will utilize btrfs_bio::iter to record the original bi_iter, for all endio functions to iterate the original range. Thus this patch will introduce a new helper, btrfs_bio_save_iter(), to save bi_iter into btrfs_bio::iter. All path that can lead to an bio_endio() call needs such btrfs_bio_save_iter() call. Under most common case, there will be a btrfs_map_bio() call to handle submitted bios. While for other error out paths, we need to call btrfs_bio_save_iter() manually, or later endio functions will ASSERT() on empty btrfs_bio::iter. Signed-off-by: Qu Wenruo <redacted> --- fs/btrfs/compression.c | 3 +++ fs/btrfs/disk-io.c | 2 ++ fs/btrfs/extent_io.c | 7 +++++++ fs/btrfs/raid56.c | 2 ++ fs/btrfs/volumes.c | 1 + fs/btrfs/volumes.h | 17 +++++++++++++++++ 6 files changed, 32 insertions(+)
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index e776956d5bc9..cc8d13369f53 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c@@ -870,6 +870,9 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, /* include any pages we added in add_ra-bio_pages */ cb->len = bio->bi_iter.bi_size; + /* Save bi_iter so that end_bio_extent_readpage() won't freak out. */ + btrfs_bio_save_iter(btrfs_bio(bio)); + while (cur_disk_byte < disk_bytenr + compressed_len) { u64 offset = cur_disk_byte - disk_bytenr; unsigned int index = offset >> PAGE_SHIFT;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 5c598e124c25..76b3fbcb91eb 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c@@ -817,6 +817,7 @@ 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 (async->status) { async->bio->bi_status = async->status; + btrfs_bio_save_iter(btrfs_bio(async->bio)); bio_endio(async->bio); return; }
@@ -949,6 +950,7 @@ blk_status_t btrfs_submit_metadata_bio(struct inode *inode, struct bio *bio, out_w_error: bio->bi_status = ret; + btrfs_bio_save_iter(btrfs_bio(bio)); bio_endio(bio); return ret; }
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 1a67f4b3986b..efd109caf95b 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c@@ -175,6 +175,11 @@ int __must_check submit_one_bio(struct bio *bio, int mirror_num, /* Caller should ensure the bio has at least some range added */ ASSERT(bio->bi_iter.bi_size); + /* + * This for later endio on errors, as later endio functions will rely + * on btrfs_bio::iter. + */ + btrfs_bio_save_iter(btrfs_bio(bio)); if (is_data_inode(tree->private_data)) ret = btrfs_submit_data_bio(tree->private_data, bio, mirror_num, bio_flags);
@@ -192,6 +197,7 @@ static void end_write_bio(struct extent_page_data *epd, int ret) if (bio) { bio->bi_status = errno_to_blk_status(ret); + btrfs_bio_save_iter(btrfs_bio(bio)); bio_endio(bio); epd->bio_ctrl.bio = NULL; }
@@ -3355,6 +3361,7 @@ static int alloc_new_bio(struct btrfs_inode *inode, error: bio_ctrl->bio = NULL; bio->bi_status = errno_to_blk_status(ret); + btrfs_bio_save_iter(btrfs_bio(bio)); bio_endio(bio); return ret; }
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 0e239a4c3b26..13e726c88a81 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c@@ -1731,6 +1731,7 @@ int raid56_parity_write(struct bio *bio, struct btrfs_io_context *bioc, return PTR_ERR(rbio); } bio_list_add(&rbio->bio_list, bio); + btrfs_bio_save_iter(btrfs_bio(bio)); rbio->bio_list_bytes = bio->bi_iter.bi_size; rbio->operation = BTRFS_RBIO_WRITE;
@@ -2135,6 +2136,7 @@ int raid56_parity_recover(struct bio *bio, struct btrfs_io_context *bioc, rbio->operation = BTRFS_RBIO_READ_REBUILD; bio_list_add(&rbio->bio_list, bio); + btrfs_bio_save_iter(btrfs_bio(bio)); rbio->bio_list_bytes = bio->bi_iter.bi_size; rbio->faila = find_logical_bio_stripe(rbio, bio);
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index f38c230111be..cdf5725f1f32 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c@@ -6794,6 +6794,7 @@ blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio, map_length = length; btrfs_bio_counter_inc_blocked(fs_info); + btrfs_bio_save_iter(btrfs_bio(bio)); ret = __btrfs_map_block(fs_info, btrfs_op(bio), logical, &map_length, &bioc, mirror_num, 1); if (ret) {
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 3b8130680749..c038fb1e36d5 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h@@ -334,6 +334,12 @@ struct btrfs_bio { struct btrfs_device *device; u8 *csum; u8 csum_inline[BTRFS_BIO_INLINE_CSUM_SIZE]; + /* + * Saved bio::bi_iter before submission. + * + * This allows us to interate the cloned/split bio properly, as at + * endio time bio::bi_iter is no longer reliable. + */ struct bvec_iter iter; /*
@@ -356,6 +362,17 @@ static inline void btrfs_bio_free_csum(struct btrfs_bio *bbio) } } +/* + * To save bbio::bio->bi_iter into bbio::iter so for callers who need the + * original bi_iter can access the original part of the bio. + * This is especially important for the incoming split btrfs_bio, which needs + * to call its endio for and only for the split range. + */ +static inline void btrfs_bio_save_iter(struct btrfs_bio *bbio) +{ + bbio->iter = bbio->bio.bi_iter; +} + struct btrfs_io_stripe { struct btrfs_device *dev; u64 physical;
--
2.34.1