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btrfs: zero out left over bytes after processing compression streams

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Don Bailey noticed that our page zeroing for compression at end-io time
isn't complete.  This reworks a patch from Linus to push the zeroing
into the zlib and lzo specific functions instead of trying to handle the
corners inside btrfs_decompress_buf2page

Signed-off-by: Chris Mason <clm@fb.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Reported-by: Don A. Bailey <donb@securitymouse.com>
cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Chris Mason
2014-11-30 08:56:33 -05:00
committed by Linus Torvalds
parent 7a5a4f9787
commit 2f19cad94c
4 changed files with 67 additions and 5 deletions
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33
fs/btrfs/compression.c
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@@ -1011,8 +1011,6 @@ int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
bytes = min(bytes, working_bytes);
kaddr = kmap_atomic(page_out);
memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);
if (*pg_index == (vcnt - 1) && *pg_offset == 0)
memset(kaddr + bytes, 0, PAGE_CACHE_SIZE - bytes);
kunmap_atomic(kaddr);
flush_dcache_page(page_out);
@@ -1054,3 +1052,34 @@ int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
return 1;
}
/*
* When uncompressing data, we need to make sure and zero any parts of
* the biovec that were not filled in by the decompression code. pg_index
* and pg_offset indicate the last page and the last offset of that page
* that have been filled in. This will zero everything remaining in the
* biovec.
*/
void btrfs_clear_biovec_end(struct bio_vec *bvec, int vcnt,
unsigned long pg_index,
unsigned long pg_offset)
{
while (pg_index < vcnt) {
struct page *page = bvec[pg_index].bv_page;
unsigned long off = bvec[pg_index].bv_offset;
unsigned long len = bvec[pg_index].bv_len;
if (pg_offset < off)
pg_offset = off;
if (pg_offset < off + len) {
unsigned long bytes = off + len - pg_offset;
char *kaddr;
kaddr = kmap_atomic(page);
memset(kaddr + pg_offset, 0, bytes);
kunmap_atomic(kaddr);
}
pg_index++;
pg_offset = 0;
}
}