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Btrfs: btrfs_submit_direct_hook: Handle map_length < bio vector length

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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@linux.vnet.ibm.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Chandan Rajendra 2016-01-21 15:56:00 +05:30 committed by David Sterba
parent 298cfd3683
commit 5f4dc8fc83
1 changed files with 17 additions and 8 deletions
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25
fs/btrfs/inode.c
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@ -8244,9 +8244,11 @@ 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,
@ -8276,9 +8278,12 @@ 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
@ -8299,7 +8304,6 @@ 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);
@ -8317,9 +8321,14 @@ 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++;
}
}