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btrfs: get rid of one layer of bios in direct I/O

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In the worst case, there are _4_ layers of bios in the Btrfs direct I/O
path:

1. The bio created by the generic direct I/O code (dio_bio).
2. A clone of dio_bio we create in btrfs_submit_direct() to represent
   the entire direct I/O range (orig_bio).
3. A partial clone of orig_bio limited to the size of a RAID stripe that
   we create in btrfs_submit_direct_hook().
4. Clones of each of those split bios for each RAID stripe that we
   create in btrfs_map_bio().

As of the previous commit, the second layer (orig_bio) is no longer
needed for anything: we can split dio_bio instead, and complete dio_bio
directly when all of the cloned bios complete. This lets us clean up a
bunch of cruft, including dip->subio_endio and dip->errors (we can use
dio_bio->bi_status instead). It also enables the next big cleanup of
direct I/O read repair.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Omar Sandoval
2020-04-16 14:46:22 -07:00
committed by David Sterba
parent 85879573fc
commit 769b4f2497
2 changed files with 65 additions and 136 deletions
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16
fs/btrfs/btrfs_inode.h
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@@ -294,11 +294,8 @@ static inline int btrfs_inode_in_log(struct btrfs_inode *inode, u64 generation)
return ret;
}
#define BTRFS_DIO_ORIG_BIO_SUBMITTED 0x1
struct btrfs_dio_private {
struct inode *inode;
unsigned long flags;
u64 logical_offset;
u64 disk_bytenr;
u64 bytes;
@@ -309,22 +306,9 @@ struct btrfs_dio_private {
*/
refcount_t refs;
/* IO errors */
int errors;
/* orig_bio is our btrfs_io_bio */
struct bio *orig_bio;
/* dio_bio came from fs/direct-io.c */
struct bio *dio_bio;
/*
* The original bio may be split to several sub-bios, this is
* done during endio of sub-bios
*/
blk_status_t (*subio_endio)(struct inode *, struct btrfs_io_bio *,
blk_status_t);
/* Array of checksums */
u8 csums[];
};