kernel/linux.git/fs/verity/verify.c, branch v6.3

fsverity: Remove WQ_UNBOUND from fsverity read workqueue

2023-03-14T23:16:36+00:00

WQ_UNBOUND causes significant scheduler latency on ARM64/Android. This is problematic for latency sensitive workloads, like I/O post-processing. Removing WQ_UNBOUND gives a 96% reduction in fsverity workqueue related scheduler latency and improves app cold startup times by ~30ms. WQ_UNBOUND was also removed from the dm-verity workqueue for the same reason [1]. This code was tested by running Android app startup benchmarks and measuring how long the fsverity workqueue spent in the runnable state. Before Total workqueue scheduler latency: 553800us After Total workqueue scheduler latency: 18962us [1]: https://lore.kernel.org/all/20230202012348.885402-1-nhuck@google.com/ Signed-off-by: Nathan Huckleberry Fixes: 8a1d0f9cacc9 ("fs-verity: add data verification hooks for ->readpages()") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230310193325.620493-1-nhuck@google.com Signed-off-by: Eric Biggers

fsverity: support verifying data from large folios

2023-01-27T22:46:31+00:00

Try to make fs/verity/verify.c aware of large folios. This includes making fsverity_verify_bio() support the case where the bio contains large folios, and adding a function fsverity_verify_folio() which is the equivalent of fsverity_verify_page(). There's no way to actually test this with large folios yet, but I've tested that this doesn't cause any regressions. Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20230127221529.299560-1-ebiggers@kernel.org

fsverity: support verification with tree block size < PAGE_SIZE

2023-01-10T03:06:03+00:00

Add support for verifying data from verity files whose Merkle tree block size is less than the page size. The main use case for this is to allow a single Merkle tree block size to be used across all systems, so that only one set of fsverity file digests and signatures is needed. To do this, eliminate various assumptions that the Merkle tree block size and the page size are the same: - Make fsverity_verify_page() a wrapper around a new function fsverity_verify_blocks() which verifies one or more blocks in a page. - When a Merkle tree block is needed, get the corresponding page and only verify and use the needed portion. (The Merkle tree continues to be read and cached in page-sized chunks; that doesn't need to change.) - When the Merkle tree block size and page size differ, use a bitmap fsverity_info::hash_block_verified to keep track of which Merkle tree blocks have been verified, as PageChecked cannot be used directly. Signed-off-by: Eric Biggers Reviewed-by: Andrey Albershteyn Tested-by: Ojaswin Mujoo Link: https://lore.kernel.org/r/20221223203638.41293-7-ebiggers@kernel.org

fsverity: replace fsverity_hash_page() with fsverity_hash_block()

2023-01-10T03:06:01+00:00

In preparation for allowing the Merkle tree block size to differ from PAGE_SIZE, replace fsverity_hash_page() with fsverity_hash_block(). The new function is similar to the old one, but it operates on the block at the given offset in the page instead of on the full page. (For now, all callers still pass a full page.) Signed-off-by: Eric Biggers Reviewed-by: Andrey Albershteyn Tested-by: Ojaswin Mujoo Link: https://lore.kernel.org/r/20221223203638.41293-6-ebiggers@kernel.org

fsverity: store log2(digest_size) precomputed

2023-01-10T03:05:56+00:00

Add log_digestsize to struct merkle_tree_params so that it can be used in verify.c. Also save memory by using u8 for all the log_* fields. Signed-off-by: Eric Biggers Reviewed-by: Andrey Albershteyn Tested-by: Ojaswin Mujoo Link: https://lore.kernel.org/r/20221223203638.41293-4-ebiggers@kernel.org

fsverity: simplify Merkle tree readahead size calculation

2023-01-10T03:05:54+00:00

First, calculate max_ra_pages more efficiently by using the bio size. Second, calculate the number of readahead pages from the hash page index, instead of calculating it ahead of time using the data page index. This ends up being a bit simpler, especially since level 0 is last in the tree, so we can just limit the readahead to the tree size. Signed-off-by: Eric Biggers Reviewed-by: Andrey Albershteyn Tested-by: Ojaswin Mujoo Link: https://lore.kernel.org/r/20221223203638.41293-3-ebiggers@kernel.org

fsverity: remove debug messages and CONFIG_FS_VERITY_DEBUG

2023-01-01T23:46:48+00:00

I've gotten very little use out of these debug messages, and I'm not aware of anyone else having used them. Indeed, sprinkling pr_debug around is not really a best practice these days, especially for filesystem code. Tracepoints are used instead. Let's just remove these and start from a clean slate. This change does not affect info, warning, and error messages. Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20221215060420.60692-1-ebiggers@kernel.org

fsverity: stop using PG_error to track error status

2022-11-29T07:15:10+00:00

As a step towards freeing the PG_error flag for other uses, change ext4 and f2fs to stop using PG_error to track verity errors. Instead, if a verity error occurs, just mark the whole bio as failed. The coarser granularity isn't really a problem since it isn't any worse than what the block layer provides, and errors from a multi-page readahead aren't reported to applications unless a single-page read fails too. f2fs supports compression, which makes the f2fs changes a bit more complicated than desired, but the basic premise still works. Note: there are still a few uses of PageError in f2fs, but they are on the write path, so they are unrelated and this patch doesn't touch them. Reviewed-by: Chao Yu Acked-by: Jaegeuk Kim Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20221129070401.156114-1-ebiggers@kernel.org

fs-verity: use memcpy_from_page()

2022-08-19T22:19:55+00:00

Replace extract_hash() with the memcpy_from_page() helper function. This is simpler, and it has the side effect of replacing the use of kmap_atomic() with its recommended replacement kmap_local_page(). Signed-off-by: Eric Biggers Reviewed-by: Fabio M. De Francesco Link: https://lore.kernel.org/r/20220818223903.43710-1-ebiggers@kernel.org

fs: Remove ->readpages address space operation

2022-04-01T17:45:33+00:00

All filesystems have now been converted to use ->readahead, so remove the ->readpages operation and fix all the comments that used to refer to it. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig Reviewed-by: Al Viro Acked-by: Al Viro