kernel/linux.git/fs/squashfs/block.c, branch linux-6.0.y

squashfs: extend "page actor" to handle missing pages

2022-06-17T02:58:21+00:00

Patch series "Squashfs: handle missing pages decompressing into page cache". This patchset enables Squashfs to handle missing pages when directly decompressing datablocks into the page cache. Previously if the full set of pages needed was not available, Squashfs would have to fall back to using an intermediate buffer (the older method), which is slower, involving a memcopy, and it introduces contention on a shared buffer. The first patch extends the "page actor" code to handle missing pages. The second patch updates Squashfs_readpage_block() to use the new functionality, and removes the code that falls back to using an intermediate buffer. This patchset is independent of the readahead work, and it is standalone. It can be merged on its own. But the readahead patch for efficiency also needs this patch-set. This patch (of 2): This patch extends the "page actor" code to handle missing pages. Previously if the full set of pages needed to decompress a Squashfs datablock was unavailable, this would cause decompression to fail on the missing pages. In this case direct decompression into the page cache could not be achieved and the code would fall back to using the older intermediate buffer method. With this patch, direct decompression into the page cache can be achieved with missing pages. For "multi-shot" decompressors (zlib, xz, zstd), the page actor will allocate a temporary buffer which is passed to the decompressor, and then freed by the page actor. For "single shot" decompressors (lz4, lzo) which decompress into a contiguous "bounce buffer", and which is then copied into the page cache, it would be pointless to allocate a temporary buffer, memcpy into it, and then free it. For these decompressors -ENOMEM is returned, which signifies that the memcpy for that page should be skipped. This also happens if the data block is uncompressed. Link: https://lkml.kernel.org/r/20220611032133.5743-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20220611032133.5743-2-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher Cc: Matthew Wilcox (Oracle) Cc: Hsin-Yi Wang Cc: Xiongwei Song Signed-off-by: Andrew Morton

block: turn bio_kmalloc into a simple kmalloc wrapper

2022-04-18T01:30:41+00:00

Remove the magic autofree semantics and require the callers to explicitly call bio_init to initialize the bio. This allows bio_free to catch accidental bio_put calls on bio_init()ed bios as well. Signed-off-by: Christoph Hellwig Acked-by: Coly Li Acked-by: Mike Snitzer Link: https://lore.kernel.org/r/20220406061228.410163-5-hch@lst.de Signed-off-by: Jens Axboe

squashfs: always use bio_kmalloc in squashfs_bio_read

2022-04-18T01:29:41+00:00

If a plain kmalloc that is not backed by a mempool is safe here for a large read (and the actual page allocations), it must also be for a small one, so simplify the code a bit. Signed-off-by: Christoph Hellwig Acked-by: Phillip Lougher Reviewed-by: Chaitanya Kulkarni Link: https://lore.kernel.org/r/20220406061228.410163-3-hch@lst.de Signed-off-by: Jens Axboe

block: pass a block_device and opf to bio_alloc

2022-02-02T14:49:59+00:00

Pass the block_device and operation that we plan to use this bio for to bio_alloc to optimize the assignment. NULL/0 can be passed, both for the passthrough case on a raw request_queue and to temporarily avoid refactoring some nasty code. Also move the gfp_mask argument after the nr_vecs argument for a much more logical calling convention matching what most of the kernel does. Signed-off-by: Christoph Hellwig Reviewed-by: Chaitanya Kulkarni Link: https://lore.kernel.org/r/20220124091107.642561-18-hch@lst.de Signed-off-by: Jens Axboe

squashfs: use bvec_virt

2021-08-16T16:50:32+00:00

Use bvec_virt instead of open coding it. Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20210804095634.460779-7-hch@lst.de Signed-off-by: Jens Axboe

squashfs: add option to panic on errors

2021-06-29T17:53:46+00:00

Add an errors=panic mount option to make squashfs trigger a panic when errors are encountered, similar to several other filesystems. This allows a kernel dump to be saved using which the corruption can be analysed and debugged. Inspired by a pre-fs_context patch by Anton Eliasson. Link: https://lkml.kernel.org/r/20210527125019.14511-1-vincent.whitchurch@axis.com Signed-off-by: Vincent Whitchurch Signed-off-by: Phillip Lougher Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

block: rename BIO_MAX_PAGES to BIO_MAX_VECS

2021-03-11T14:47:48+00:00

Ever since the addition of multipage bio_vecs BIO_MAX_PAGES has been horribly confusingly misnamed. Rename it to BIO_MAX_VECS to stop confusing users of the bio API. Signed-off-by: Christoph Hellwig Reviewed-by: Matthew Wilcox (Oracle) Reviewed-by: Martin K. Petersen Link: https://lore.kernel.org/r/20210311110137.1132391-2-hch@lst.de Signed-off-by: Jens Axboe

squashfs: avoid out of bounds writes in decompressors

2021-02-10T01:26:44+00:00

Patch series "Squashfs: fix BIO migration regression and add sanity checks". Patch [1/4] fixes a regression introduced by the "migrate from ll_rw_block usage to BIO" patch, which has produced a number of Sysbot/Syzkaller reports. Patches [2/4], [3/4], and [4/4] fix a number of filesystem corruption issues which have produced Sysbot reports in the id, inode and xattr lookup code. Each patch has been tested against the Sysbot reproducers using the given kernel configuration. They have the appropriate "Reported-by:" lines added. Additionally, all of the reproducer filesystems are indirectly fixed by patch [4/4] due to the fact they all have xattr corruption which is now detected there. Additional testing with other configurations and architectures (32bit, big endian), and normal filesystems has also been done to trap any inadvertent regressions caused by the additional sanity checks. This patch (of 4): This is a regression introduced by the patch "migrate from ll_rw_block usage to BIO". Sysbot/Syskaller has reported a number of "out of bounds writes" and "unable to handle kernel paging request in squashfs_decompress" errors which have been identified as a regression introduced by the above patch. Specifically, the patch removed the following sanity check if (length < 0 || length > output->length || (index + length) > msblk->bytes_used) This check did two things: 1. It ensured any reads were not beyond the end of the filesystem 2. It ensured that the "length" field read from the filesystem was within the expected maximum length. Without this any corrupted values can over-run allocated buffers. Link: https://lkml.kernel.org/r/20210204130249.4495-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20210204130249.4495-2-phillip@squashfs.org.uk Fixes: 93e72b3c612adc ("squashfs: migrate from ll_rw_block usage to BIO") Reported-by: syzbot+6fba78f99b9afd4b5634@syzkaller.appspotmail.com Signed-off-by: Phillip Lougher Cc: Philippe Liard Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

squashfs: avoid bio_alloc() failure with 1Mbyte blocks

2020-08-21T16:52:53+00:00

This is a regression introduced by the patch "migrate from ll_rw_block usage to BIO". Bio_alloc() is limited to 256 pages (1 Mbyte). This can cause a failure when reading 1 Mbyte block filesystems. The problem is a datablock can be fully (or almost uncompressed), requiring 256 pages, but, because blocks are not aligned to page boundaries, it may require 257 pages to read. Bio_kmalloc() can handle 1024 pages, and so use this for the edge condition. Fixes: 93e72b3c612a ("squashfs: migrate from ll_rw_block usage to BIO") Reported-by: Nicolas Prochazka Reported-by: Tomoatsu Shimada Signed-off-by: Phillip Lougher Signed-off-by: Andrew Morton Reviewed-by: Guenter Roeck Cc: Philippe Liard Cc: Christoph Hellwig Cc: Adrien Schildknecht Cc: Daniel Rosenberg Cc: Link: http://lkml.kernel.org/r/20200815035637.15319-1-phillip@squashfs.org.uk Signed-off-by: Linus Torvalds

squashfs: fix length field overlap check in metadata reading

2020-07-24T19:42:41+00:00

This is a regression introduced by the "migrate from ll_rw_block usage to BIO" patch. Squashfs packs structures on byte boundaries, and due to that the length field (of the metadata block) may not be fully in the current block. The new code rewrote and introduced a faulty check for that edge case. Fixes: 93e72b3c612adcaca1 ("squashfs: migrate from ll_rw_block usage to BIO") Reported-by: Bernd Amend Signed-off-by: Phillip Lougher Signed-off-by: Andrew Morton Cc: Christoph Hellwig Cc: Adrien Schildknecht Cc: Guenter Roeck Cc: Daniel Rosenberg Link: http://lkml.kernel.org/r/20200717195536.16069-1-phillip@squashfs.org.uk Signed-off-by: Linus Torvalds