Re: [PATCH V8 03/13] Btrfs: Direct I/O read: Work on sectorsized blocks

[Josef Bacik]

On 10/28/2015 04:10 AM, Chandan Rajendra wrote:

The direct I/O read's endio and corresponding repair functions work on
page sized blocks. This commit adds the ability for direct I/O read to work on
subpagesized blocks.



Reviewed-by: Josef Bacik 

Thanks,

Josef
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[PATCH V8 03/13] Btrfs: Direct I/O read: Work on sectorsized blocks

[Chandan Rajendra]

The direct I/O read's endio and corresponding repair functions work on
page sized blocks. This commit adds the ability for direct I/O read to work on
subpagesized blocks.

Signed-off-by: Chandan Rajendra 
---
 fs/btrfs/inode.c | 98 +++-
 1 file changed, 75 insertions(+), 23 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index a018e47..98d901e 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7764,9 +7764,9 @@ static int btrfs_check_dio_repairable(struct inode *inode,
 }
 
 static int dio_read_error(struct inode *inode, struct bio *failed_bio,
- struct page *page, u64 start, u64 end,
- int failed_mirror, bio_end_io_t *repair_endio,
- void *repair_arg)
+   struct page *page, unsigned int pgoff,
+   u64 start, u64 end, int failed_mirror,
+   bio_end_io_t *repair_endio, void *repair_arg)
 {
struct io_failure_record *failrec;
struct bio *bio;
@@ -7787,7 +7787,9 @@ static int dio_read_error(struct inode *inode, struct bio 
*failed_bio,
return -EIO;
}
 
-   if (failed_bio->bi_vcnt > 1)
+   if ((failed_bio->bi_vcnt > 1)
+   || (failed_bio->bi_io_vec->bv_len
+   > BTRFS_I(inode)->root->sectorsize))
read_mode = READ_SYNC | REQ_FAILFAST_DEV;
else
read_mode = READ_SYNC;
@@ -7795,7 +7797,7 @@ static int dio_read_error(struct inode *inode, struct bio 
*failed_bio,
isector = start - btrfs_io_bio(failed_bio)->logical;
isector >>= inode->i_sb->s_blocksize_bits;
bio = btrfs_create_repair_bio(inode, failed_bio, failrec, page,
- 0, isector, repair_endio, repair_arg);
+   pgoff, isector, repair_endio, repair_arg);
if (!bio) {
free_io_failure(inode, failrec);
return -EIO;
@@ -7825,12 +7827,17 @@ struct btrfs_retry_complete {
 static void btrfs_retry_endio_nocsum(struct bio *bio)
 {
struct btrfs_retry_complete *done = bio->bi_private;
+   struct inode *inode;
struct bio_vec *bvec;
int i;
 
if (bio->bi_error)
goto end;
 
+   ASSERT(bio->bi_vcnt == 1);
+   inode = bio->bi_io_vec->bv_page->mapping->host;
+   ASSERT(bio->bi_io_vec->bv_len == BTRFS_I(inode)->root->sectorsize);
+
done->uptodate = 1;
bio_for_each_segment_all(bvec, bio, i)
clean_io_failure(done->inode, done->start, bvec->bv_page, 0);
@@ -7842,25 +7849,35 @@ end:
 static int __btrfs_correct_data_nocsum(struct inode *inode,
   struct btrfs_io_bio *io_bio)
 {
+   struct btrfs_fs_info *fs_info;
struct bio_vec *bvec;
struct btrfs_retry_complete done;
u64 start;
+   unsigned int pgoff;
+   u32 sectorsize;
+   int nr_sectors;
int i;
int ret;
 
+   fs_info = BTRFS_I(inode)->root->fs_info;
+   sectorsize = BTRFS_I(inode)->root->sectorsize;
+
start = io_bio->logical;
done.inode = inode;
 
bio_for_each_segment_all(bvec, &io_bio->bio, i) {
-try_again:
+   nr_sectors = BTRFS_BYTES_TO_BLKS(fs_info, bvec->bv_len);
+   pgoff = bvec->bv_offset;
+
+next_block_or_try_again:
done.uptodate = 0;
done.start = start;
init_completion(&done.done);
 
-   ret = dio_read_error(inode, &io_bio->bio, bvec->bv_page, start,
-start + bvec->bv_len - 1,
-io_bio->mirror_num,
-btrfs_retry_endio_nocsum, &done);
+   ret = dio_read_error(inode, &io_bio->bio, bvec->bv_page,
+   pgoff, start, start + sectorsize - 1,
+   io_bio->mirror_num,
+   btrfs_retry_endio_nocsum, &done);
if (ret)
return ret;
 
@@ -7868,10 +7885,15 @@ try_again:
 
if (!done.uptodate) {
/* We might have another mirror, so try again */
-   goto try_again;
+   goto next_block_or_try_again;
}
 
-   start += bvec->bv_len;
+   start += sectorsize;
+
+   if (nr_sectors--) {
+   pgoff += sectorsize;
+   goto next_block_or_try_again;
+   }
}
 
return 0;
@@ -7881,7 +7903,9 @@ static void btrfs_retry_endio(struct bio *bio)
 {
struct btrfs_retry_complete *done = bio->bi_private;
struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
+   struct inode *inode;
struct bio_vec *bvec;
+   u64 start;
int uptodate;
int ret;
int i;
@