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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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20
fs/btrfs/zlib.c
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@ -299,6 +299,8 @@ done:
zlib_inflateEnd(&workspace->strm);
if (data_in)
kunmap(pages_in[page_in_index]);
if (!ret)
btrfs_clear_biovec_end(bvec, vcnt, page_out_index, pg_offset);
return ret;
}
@ -310,10 +312,14 @@ static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
struct workspace *workspace = list_entry(ws, struct workspace, list);
int ret = 0;
int wbits = MAX_WBITS;
unsigned long bytes_left = destlen;
unsigned long bytes_left;
unsigned long total_out = 0;
unsigned long pg_offset = 0;
char *kaddr;
destlen = min_t(unsigned long, destlen, PAGE_SIZE);
bytes_left = destlen;
workspace->strm.next_in = data_in;
workspace->strm.avail_in = srclen;
workspace->strm.total_in = 0;
@ -341,7 +347,6 @@ static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
unsigned long buf_start;
unsigned long buf_offset;
unsigned long bytes;
unsigned long pg_offset = 0;
ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END)
@ -384,6 +389,17 @@ next:
ret = 0;
zlib_inflateEnd(&workspace->strm);
/*
* this should only happen if zlib returned fewer bytes than we
* expected. btrfs_get_block is responsible for zeroing from the
* end of the inline extent (destlen) to the end of the page
*/
if (pg_offset < destlen) {
kaddr = kmap_atomic(dest_page);
memset(kaddr + pg_offset, 0, destlen - pg_offset);
kunmap_atomic(kaddr);
}
return ret;
}