Currently all reads of the fsverity hashes is kicked off from the data I/O completion handler, leading to needlessly dependent I/O. This is worked around a bit by performing readahead on the level 0 nodes, but still fairly ineffective.
Switch to a model where the ->read_folio and ->readahead methods instead kick off explicit readahead of the fsverity hashed so they are usually available at I/O completion time. For 64k sequential reads on my test VM this improves read performance from 2.4GB/s - 2.6GB/s to 3.5GB/s - 3.9GB/s. The improvements for random reads are likely to be even bigger. Signed-off-by: Christoph Hellwig <[email protected]> --- fs/btrfs/verity.c | 4 +- fs/ext4/readpage.c | 4 ++ fs/ext4/verity.c | 26 +++++------ fs/f2fs/data.c | 4 ++ fs/f2fs/verity.c | 26 +++++------ fs/verity/read_metadata.c | 10 ++--- fs/verity/verify.c | 92 ++++++++++++++++++++++++++++----------- include/linux/fsverity.h | 34 ++++++++++++--- 8 files changed, 132 insertions(+), 68 deletions(-) diff --git a/fs/btrfs/verity.c b/fs/btrfs/verity.c index 8a4426f8b5fb..cd96fac4739f 100644 --- a/fs/btrfs/verity.c +++ b/fs/btrfs/verity.c @@ -697,7 +697,6 @@ int btrfs_get_verity_descriptor(struct inode *inode, void *buf, size_t buf_size) * * @inode: inode to read a merkle tree page for * @index: page index relative to the start of the merkle tree - * @num_ra_pages: number of pages to readahead. Optional, we ignore it * * The Merkle tree is stored in the filesystem btree, but its pages are cached * with a logical position past EOF in the inode's mapping. @@ -705,8 +704,7 @@ int btrfs_get_verity_descriptor(struct inode *inode, void *buf, size_t buf_size) * Returns the page we read, or an ERR_PTR on error. */ static struct page *btrfs_read_merkle_tree_page(struct inode *inode, - pgoff_t index, - unsigned long num_ra_pages) + pgoff_t index) { struct folio *folio; u64 off = (u64)index << PAGE_SHIFT; diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c index e7f2350c725b..56b3bea657ef 100644 --- a/fs/ext4/readpage.c +++ b/fs/ext4/readpage.c @@ -226,6 +226,7 @@ int ext4_mpage_readpages(struct inode *inode, unsigned relative_block = 0; struct ext4_map_blocks map; unsigned int nr_pages, folio_pages; + unsigned int did_fsverity_readahead = 0; map.m_pblk = 0; map.m_lblk = 0; @@ -241,6 +242,9 @@ int ext4_mpage_readpages(struct inode *inode, if (rac) folio = readahead_folio(rac); + if (!did_fsverity_readahead++) + fsverity_readahead(inode, folio->index, nr_pages); + folio_pages = folio_nr_pages(folio); prefetchw(&folio->flags); diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c index 2cd6fe2fbf64..baa7277dcf1f 100644 --- a/fs/ext4/verity.c +++ b/fs/ext4/verity.c @@ -358,28 +358,25 @@ static int ext4_get_verity_descriptor(struct inode *inode, void *buf, } static struct page *ext4_read_merkle_tree_page(struct inode *inode, - pgoff_t index, - unsigned long num_ra_pages) + pgoff_t index) { struct folio *folio; index += ext4_verity_metadata_pos(inode) >> PAGE_SHIFT; - folio = __filemap_get_folio(inode->i_mapping, index, FGP_ACCESSED, 0); - if (IS_ERR(folio) || !folio_test_uptodate(folio)) { - DEFINE_READAHEAD(ractl, NULL, NULL, inode->i_mapping, index); - - if (!IS_ERR(folio)) - folio_put(folio); - else if (num_ra_pages > 1) - page_cache_ra_unbounded(&ractl, num_ra_pages, 0); - folio = read_mapping_folio(inode->i_mapping, index, NULL); - if (IS_ERR(folio)) - return ERR_CAST(folio); - } + folio = read_mapping_folio(inode->i_mapping, index, NULL); + if (IS_ERR(folio)) + return ERR_CAST(folio); return folio_file_page(folio, index); } +static void ext4_readahead_merkle_tree(struct inode *inode, pgoff_t index, + unsigned long nr_pages) +{ + index += ext4_verity_metadata_pos(inode) >> PAGE_SHIFT; + generic_readahead_merkle_tree(inode, index, nr_pages); +} + static int ext4_write_merkle_tree_block(struct file *file, const void *buf, u64 pos, unsigned int size) { @@ -393,5 +390,6 @@ const struct fsverity_operations ext4_verityops = { .end_enable_verity = ext4_end_enable_verity, .get_verity_descriptor = ext4_get_verity_descriptor, .read_merkle_tree_page = ext4_read_merkle_tree_page, + .readahead_merkle_tree = ext4_readahead_merkle_tree, .write_merkle_tree_block = ext4_write_merkle_tree_block, }; diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index c30e69392a62..c01d5b309751 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -2359,6 +2359,7 @@ static int f2fs_mpage_readpages(struct inode *inode, unsigned nr_pages = rac ? readahead_count(rac) : 1; unsigned max_nr_pages = nr_pages; int ret = 0; + unsigned int did_fsverity_readahead = 0; #ifdef CONFIG_F2FS_FS_COMPRESSION if (f2fs_compressed_file(inode)) { @@ -2383,6 +2384,9 @@ static int f2fs_mpage_readpages(struct inode *inode, prefetchw(&folio->flags); } + if (!did_fsverity_readahead++) + fsverity_readahead(inode, folio->index, nr_pages); + #ifdef CONFIG_F2FS_FS_COMPRESSION index = folio->index; diff --git a/fs/f2fs/verity.c b/fs/f2fs/verity.c index 4326fd72cc72..1ce977937c72 100644 --- a/fs/f2fs/verity.c +++ b/fs/f2fs/verity.c @@ -256,28 +256,25 @@ static int f2fs_get_verity_descriptor(struct inode *inode, void *buf, } static struct page *f2fs_read_merkle_tree_page(struct inode *inode, - pgoff_t index, - unsigned long num_ra_pages) + pgoff_t index) { struct folio *folio; index += f2fs_verity_metadata_pos(inode) >> PAGE_SHIFT; - folio = f2fs_filemap_get_folio(inode->i_mapping, index, FGP_ACCESSED, 0); - if (IS_ERR(folio) || !folio_test_uptodate(folio)) { - DEFINE_READAHEAD(ractl, NULL, NULL, inode->i_mapping, index); - - if (!IS_ERR(folio)) - folio_put(folio); - else if (num_ra_pages > 1) - page_cache_ra_unbounded(&ractl, num_ra_pages, 0); - folio = read_mapping_folio(inode->i_mapping, index, NULL); - if (IS_ERR(folio)) - return ERR_CAST(folio); - } + folio = read_mapping_folio(inode->i_mapping, index, NULL); + if (IS_ERR(folio)) + return ERR_CAST(folio); return folio_file_page(folio, index); } +static void f2fs_readahead_merkle_tree(struct inode *inode, pgoff_t index, + unsigned long nr_pages) +{ + index += f2fs_verity_metadata_pos(inode) >> PAGE_SHIFT; + generic_readahead_merkle_tree(inode, index, nr_pages); +} + static int f2fs_write_merkle_tree_block(struct file *file, const void *buf, u64 pos, unsigned int size) { @@ -291,5 +288,6 @@ const struct fsverity_operations f2fs_verityops = { .end_enable_verity = f2fs_end_enable_verity, .get_verity_descriptor = f2fs_get_verity_descriptor, .read_merkle_tree_page = f2fs_read_merkle_tree_page, + .readahead_merkle_tree = f2fs_readahead_merkle_tree, .write_merkle_tree_block = f2fs_write_merkle_tree_block, }; diff --git a/fs/verity/read_metadata.c b/fs/verity/read_metadata.c index cba5d6af4e04..3abaa0a4c40e 100644 --- a/fs/verity/read_metadata.c +++ b/fs/verity/read_metadata.c @@ -28,24 +28,24 @@ static int fsverity_read_merkle_tree(struct inode *inode, if (offset >= end_offset) return 0; offs_in_page = offset_in_page(offset); + index = offset >> PAGE_SHIFT; last_index = (end_offset - 1) >> PAGE_SHIFT; + __fsverity_readahead(inode, vi, index, last_index - index + 1); + /* * Iterate through each Merkle tree page in the requested range and copy * the requested portion to userspace. Note that the Merkle tree block * size isn't important here, as we are returning a byte stream; i.e., * we can just work with pages even if the tree block size != PAGE_SIZE. */ - for (index = offset >> PAGE_SHIFT; index <= last_index; index++) { - unsigned long num_ra_pages = - min_t(unsigned long, last_index - index + 1, - inode->i_sb->s_bdi->io_pages); + for (; index <= last_index; index++) { unsigned int bytes_to_copy = min_t(u64, end_offset - offset, PAGE_SIZE - offs_in_page); struct page *page; const void *virt; - page = vops->read_merkle_tree_page(inode, index, num_ra_pages); + page = vops->read_merkle_tree_page(inode, index); if (IS_ERR(page)) { err = PTR_ERR(page); fsverity_err(inode, diff --git a/fs/verity/verify.c b/fs/verity/verify.c index 3cc81658e4f3..9a96bad82938 100644 --- a/fs/verity/verify.c +++ b/fs/verity/verify.c @@ -9,6 +9,7 @@ #include <linux/bio.h> #include <linux/export.h> +#include <linux/pagemap.h> #define FS_VERITY_MAX_PENDING_BLOCKS 2 @@ -21,7 +22,6 @@ struct fsverity_pending_block { struct fsverity_verification_context { struct inode *inode; struct fsverity_info *vi; - unsigned long max_ra_pages; /* * This is the queue of data blocks that are pending verification. When @@ -37,6 +37,65 @@ struct fsverity_verification_context { static struct workqueue_struct *fsverity_read_workqueue; +/** + * generic_readahead_merkle_tree() - read ahead from merkle tree + * @inode: inode containing fsverity hashes + * @index: first data page offset to read ahead for + * @nr_pages: number of data pages to read ahead for + * + * Generic fsverity hashes read implementations for file systems storing + * the hashes in the page cache of the data inode. The caller needs to + * adjust @index for the fsverity hash offset. + */ +void generic_readahead_merkle_tree(struct inode *inode, pgoff_t index, + unsigned long nr_pages) +{ + struct folio *folio; + + folio = __filemap_get_folio(inode->i_mapping, index, FGP_ACCESSED, 0); + if (PTR_ERR(folio) == -ENOENT || !folio_test_uptodate(folio)) { + DEFINE_READAHEAD(ractl, NULL, NULL, inode->i_mapping, index); + + page_cache_ra_unbounded(&ractl, nr_pages, 0); + } + if (!IS_ERR(folio)) + folio_put(folio); +} +EXPORT_SYMBOL_GPL(generic_readahead_merkle_tree); + +void __fsverity_readahead(struct inode *inode, const struct fsverity_info *vi, + pgoff_t index, unsigned long nr_pages) +{ + const struct merkle_tree_params *params = &vi->tree_params; + loff_t data_start_pos = (loff_t)index << PAGE_SHIFT; + u64 start_hidx = data_start_pos >> params->log_blocksize; + u64 end_hidx = (data_start_pos + ((nr_pages - 1) << PAGE_SHIFT)) >> + params->log_blocksize; + int level; + + if (!inode->i_sb->s_vop->readahead_merkle_tree) + return; + if (unlikely(data_start_pos >= inode->i_size)) + return; + + for (level = 0; level < params->num_levels; level++) { + unsigned long level_start = params->level_start[level]; + unsigned long next_start_hidx = start_hidx >> params->log_arity; + unsigned long next_end_hidx = end_hidx >> params->log_arity; + unsigned long start_idx = (level_start + next_start_hidx) >> + params->log_blocks_per_page; + unsigned long end_idx = (level_start + next_end_hidx) >> + params->log_blocks_per_page; + + inode->i_sb->s_vop->readahead_merkle_tree(inode, start_idx, + end_idx - start_idx + 1); + + start_hidx = next_start_hidx; + end_hidx = next_end_hidx; + } +} +EXPORT_SYMBOL_GPL(__fsverity_readahead); + /* * Returns true if the hash block with index @hblock_idx in the tree, located in * @hpage, has already been verified. @@ -114,8 +173,7 @@ static bool is_hash_block_verified(struct fsverity_info *vi, struct page *hpage, * Return: %true if the data block is valid, else %false. */ static bool verify_data_block(struct inode *inode, struct fsverity_info *vi, - const struct fsverity_pending_block *dblock, - unsigned long max_ra_pages) + const struct fsverity_pending_block *dblock) { const u64 data_pos = dblock->pos; const struct merkle_tree_params *params = &vi->tree_params; @@ -200,8 +258,7 @@ static bool verify_data_block(struct inode *inode, struct fsverity_info *vi, (params->block_size - 1); hpage = inode->i_sb->s_vop->read_merkle_tree_page(inode, - hpage_idx, level == 0 ? min(max_ra_pages, - params->tree_pages - hpage_idx) : 0); + hpage_idx); if (IS_ERR(hpage)) { fsverity_err(inode, "Error %ld reading Merkle tree page %lu", @@ -272,12 +329,10 @@ static bool verify_data_block(struct inode *inode, struct fsverity_info *vi, static void fsverity_init_verification_context(struct fsverity_verification_context *ctx, - struct inode *inode, - unsigned long max_ra_pages) + struct inode *inode) { ctx->inode = inode; ctx->vi = fsverity_get_info(inode); - ctx->max_ra_pages = max_ra_pages; ctx->num_pending = 0; if (ctx->vi->tree_params.hash_alg->algo_id == HASH_ALGO_SHA256 && sha256_finup_2x_is_optimized()) @@ -320,8 +375,7 @@ fsverity_verify_pending_blocks(struct fsverity_verification_context *ctx) } for (i = 0; i < ctx->num_pending; i++) { - if (!verify_data_block(ctx->inode, vi, &ctx->pending_blocks[i], - ctx->max_ra_pages)) + if (!verify_data_block(ctx->inode, vi, &ctx->pending_blocks[i])) return false; } fsverity_clear_pending_blocks(ctx); @@ -371,7 +425,7 @@ bool fsverity_verify_blocks(struct folio *folio, size_t len, size_t offset) { struct fsverity_verification_context ctx; - fsverity_init_verification_context(&ctx, folio->mapping->host, 0); + fsverity_init_verification_context(&ctx, folio->mapping->host); if (fsverity_add_data_blocks(&ctx, folio, len, offset) && fsverity_verify_pending_blocks(&ctx)) @@ -401,22 +455,8 @@ void fsverity_verify_bio(struct bio *bio) struct inode *inode = bio_first_folio_all(bio)->mapping->host; struct fsverity_verification_context ctx; struct folio_iter fi; - unsigned long max_ra_pages = 0; - - if (bio->bi_opf & REQ_RAHEAD) { - /* - * If this bio is for data readahead, then we also do readahead - * of the first (largest) level of the Merkle tree. Namely, - * when a Merkle tree page is read, we also try to piggy-back on - * some additional pages -- up to 1/4 the number of data pages. - * - * This improves sequential read performance, as it greatly - * reduces the number of I/O requests made to the Merkle tree. - */ - max_ra_pages = bio->bi_iter.bi_size >> (PAGE_SHIFT + 2); - } - fsverity_init_verification_context(&ctx, inode, max_ra_pages); + fsverity_init_verification_context(&ctx, inode); bio_for_each_folio_all(fi, bio) { if (!fsverity_add_data_blocks(&ctx, fi.folio, fi.length, diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h index deb6b2303d64..84aaa09e07e2 100644 --- a/include/linux/fsverity.h +++ b/include/linux/fsverity.h @@ -90,10 +90,6 @@ struct fsverity_operations { * * @inode: the inode * @index: 0-based index of the page within the Merkle tree - * @num_ra_pages: The number of Merkle tree pages that should be - * prefetched starting at @index if the page at @index - * isn't already cached. Implementations may ignore this - * argument; it's only a performance optimization. * * This can be called at any time on an open verity file. It may be * called by multiple processes concurrently, even with the same page. @@ -103,8 +99,10 @@ struct fsverity_operations { * Return: the page on success, ERR_PTR() on failure */ struct page *(*read_merkle_tree_page)(struct inode *inode, - pgoff_t index, - unsigned long num_ra_pages); + pgoff_t index); + + void (*readahead_merkle_tree)(struct inode *inode, pgoff_t index, + unsigned long nr_pages); /** * Write a Merkle tree block to the given inode. @@ -246,4 +244,28 @@ static inline bool fsverity_active(const struct inode *inode) return fsverity_get_info(inode) != NULL; } +/** + * fsverity_readahead() - kick off readahead on fsverity hashes + * @inode: inode containing fsverity hashes + * @index: first data page offset to read ahead for + * @nr_pages: number of data pages to read ahead for + * + * Start readahead on fsverity hashes. To be called from the file systems + * ->read_folio and ->readahead methods to ensure that the hashes are + * already cached on completion of the file data read if possible. + */ +void __fsverity_readahead(struct inode *inode, const struct fsverity_info *vi, + pgoff_t index, unsigned long nr_pages); +static inline void fsverity_readahead(struct inode *inode, + pgoff_t index, unsigned long nr_pages) +{ + const struct fsverity_info *vi = fsverity_get_info(inode); + + if (vi) + __fsverity_readahead(inode, vi, index, nr_pages); +} + +void generic_readahead_merkle_tree(struct inode *inode, pgoff_t index, + unsigned long nr_pages); + #endif /* _LINUX_FSVERITY_H */ -- 2.47.3 _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
