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SubjectRe: [GIT PULL] Squashfs fixes for 2.6.29?
Date
Hi

On Mittwoch, 11. März 2009, Phillip Lougher wrote:
> Phillip Lougher wrote:
[...]
> The following patch fixes the problems you've experienced with your test
> filesystems (thanks for making them available), and also deals with the corrupted
> filesystems issue. It correctly works with all the corrupted filesystems sent
> earlier this year.
>
> The problem arises due to an unexpected corner-case with zlib which the
> corrupted filesystems patch didn't address. Very occasionally zlib exits
> needing a couple of extra bytes of input (1 and 2 bytes in the test filesystems),
> but with avail_out == 0 and no more output buffers available. This situation
> was incorrectly flagged as an error by the corrupted filesystems patch. I
> unfortunately didn't anticipate this scenario because it seems contrary to
> expectation that zlib will be still reading input having produced all the
> expected output. The fix is to not print an error if zlib wants more input
> bytes and there's more input bytes to be read.

I just got home and around to test it with 2.6.29-rc7-git4, no further
issues with large filesystems (copying + live usage) and it's working
reliably (after whitespace fixing), thank you a lot.

> Geert I can put a signed off line from you on the patch if you like (as you
> sent the original fix). I could add reported and tested lines from both of you?
> They seem to be being used more often and sound a good idea.

Feel free to add the tags as needed, thanks.
Reported-by: Stefan Lippers-Hollmann <s.L-H@gmx.de>
Tested-by: Stefan Lippers-Hollmann <s.L-H@gmx.de>

> Thanks
>
> Phillip

Regards
Stefan Lippers-Hollmann

--
> diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
> index 321728f..b85173f 100644
> --- a/fs/squashfs/block.c
> +++ b/fs/squashfs/block.c
> @@ -166,6 +166,22 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
>
> bytes = length;
> do {
> + if (msblk->stream.avail_out == 0) {
> + if (page < pages) {
> + msblk->stream.next_out = buffer[page++];
> + msblk->stream.avail_out =
> + PAGE_CACHE_SIZE;
> + } else if (msblk->stream.avail_in > 0
> + || bytes == 0) {
> + ERROR("zlib_inflate tried to "
> + "decompress too much data, "
> + "expected %d bytes. Zlib "
> + "data probably corrupt\n",
> + srclength);
> + goto release_mutex;
> + }
> + }
> +
> if (msblk->stream.avail_in == 0 && k < b) {
> avail = min(bytes, msblk->devblksize - offset);
> bytes -= avail;
> @@ -184,19 +200,6 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
> offset = 0;
> }
>
> - if (msblk->stream.avail_out == 0) {
> - if (page == pages) {
> - ERROR("zlib_inflate tried to "
> - "decompress too much data, "
> - "expected %d bytes. Zlib "
> - "data probably corrupt\n",
> - srclength);
> - goto release_mutex;
> - }
> - msblk->stream.next_out = buffer[page++];
> - msblk->stream.avail_out = PAGE_CACHE_SIZE;
> - }
> -
> if (!zlib_init) {
> zlib_err = zlib_inflateInit(&msblk->stream);
> if (zlib_err != Z_OK) {
--
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