In subpagesize-blocksize scenario, map_length can be less than the length of a
bio vector. Such a condition may cause btrfs_submit_direct_hook() to submit a
zero length bio. Fix this by comparing map_length against block size rather
than with bv_len.
Signed-off-by: Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx>
---
fs/btrfs/inode.c | 25 +++++++++++++++++--------
1 file changed, 17 insertions(+), 8 deletions(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8a79e53..1826603 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8150,9 +8150,11 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip,
u64 file_offset = dip->logical_offset;
u64 submit_len = 0;
u64 map_length;
- int nr_pages = 0;
- int ret;
+ u32 blocksize = root->sectorsize;
int async_submit = 0;
+ int nr_sectors;
+ int ret;
+ int i;
map_length = orig_bio->bi_iter.bi_size;
ret = btrfs_map_block(root->fs_info, rw, start_sector << 9,
@@ -8182,9 +8184,12 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip,
atomic_inc(&dip->pending_bios);
while (bvec <= (orig_bio->bi_io_vec + orig_bio->bi_vcnt - 1)) {
- if (map_length < submit_len + bvec->bv_len ||
- bio_add_page(bio, bvec->bv_page, bvec->bv_len,
- bvec->bv_offset) < bvec->bv_len) {
+ nr_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info, bvec->bv_len);
+ i = 0;
+next_block:
+ if (unlikely(map_length < submit_len + blocksize ||
+ bio_add_page(bio, bvec->bv_page, blocksize,
+ bvec->bv_offset + (i * blocksize)) < blocksize)) {
/*
* inc the count before we submit the bio so
* we know the end IO handler won't happen before
@@ -8205,7 +8210,6 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip,
file_offset += submit_len;
submit_len = 0;
- nr_pages = 0;
bio = btrfs_dio_bio_alloc(orig_bio->bi_bdev,
start_sector, GFP_NOFS);
@@ -8223,9 +8227,14 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip,
bio_put(bio);
goto out_err;
}
+
+ goto next_block;
} else {
- submit_len += bvec->bv_len;
- nr_pages++;
+ submit_len += blocksize;
+ if (--nr_sectors) {
+ i++;
+ goto next_block;
+ }
bvec++;
}
}
--
2.1.0
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