From: Andrey Albershteyn Date: Wed, 20 May 2026 12:37:06 +0000 (+0200) Subject: iomap: teach iomap to read files with fsverity X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=1d140731753a277be36637300a0f3faa396edec1;p=thirdparty%2Flinux.git iomap: teach iomap to read files with fsverity Obtain fsverity info for folios with file data and fsverity metadata. Filesystem can pass vi down to ioend and then to fsverity for verification. This is different from other filesystems ext4, f2fs, btrfs supporting fsverity, these filesystems don't need fsverity_info for reading fsverity metadata. While reading merkle tree iomap requires fsverity info to synthesize hashes for zeroed data block. fsverity metadata has two kinds of holes - ones in merkle tree and one after fsverity descriptor. Merkle tree holes are blocks full of hashes of zeroed data blocks. These are not stored on the disk but synthesized on the fly. This saves a bit of space for sparse files. Due to this iomap also need to lookup fsverity_info for folios with fsverity metadata. ->vi has a hash of the zeroed data block which will be used to fill the merkle tree block. The hole past descriptor is interpreted as end of metadata region. As we don't have EOF here we use this hole as an indication that rest of the folio is empty. This patch marks rest of the folio beyond fsverity descriptor as uptodate. For file data, fsverity needs to verify consistency of the whole file against the root hash, hashes of holes are included in the merkle tree. Verify them too. Issue reading of fsverity merkle tree on the fsverity inodes. This way metadata will be available at I/O completion time. Reviewed-by: Darrick J. Wong Reviewed-by: Christoph Hellwig Signed-off-by: Andrey Albershteyn Link: https://patch.msgid.link/20260520123722.405752-9-aalbersh@kernel.org Signed-off-by: Christian Brauner (Amutable) --- diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index d9462f28afbd..f9cc5a32e222 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -9,6 +9,7 @@ #include #include #include +#include #include "internal.h" #include "trace.h" @@ -561,9 +562,27 @@ static int iomap_read_folio_iter(struct iomap_iter *iter, if (plen == 0) return 0; - /* zero post-eof blocks as the page may be mapped */ - if (iomap_block_needs_zeroing(iter, pos)) { + /* + * Handling of fsverity "holes". We hit this for two case: + * 1. No need to go further, the hole after fsverity + * descriptor is the end of the fsverity metadata. + * + * 2. This folio contains merkle tree blocks which need to be + * synthesized. If we already have fsverity info (ctx->vi) + * synthesize these blocks. + */ + if ((iomap->flags & IOMAP_F_FSVERITY) && + iomap->type == IOMAP_HOLE) { + if (ctx->vi) + fsverity_fill_zerohash(folio, poff, plen, + ctx->vi); + iomap_set_range_uptodate(folio, poff, plen); + } else if (iomap_block_needs_zeroing(iter, pos)) { + /* zero post-eof blocks as the page may be mapped */ folio_zero_range(folio, poff, plen); + if (ctx->vi && + !fsverity_verify_blocks(ctx->vi, folio, plen, poff)) + return -EIO; iomap_set_range_uptodate(folio, poff, plen); } else { if (!*bytes_submitted) @@ -614,6 +633,15 @@ void iomap_read_folio(const struct iomap_ops *ops, trace_iomap_readpage(iter.inode, 1); + /* + * Fetch fsverity_info for both data and fsverity metadata, as iomap + * needs zeroed hash for merkle tree block synthesis + */ + ctx->vi = fsverity_get_info(iter.inode); + if (ctx->vi && iter.pos < i_size_read(iter.inode)) + fsverity_readahead(ctx->vi, folio->index, + folio_nr_pages(folio)); + while ((ret = iomap_iter(&iter, ops)) > 0) iter.status = iomap_read_folio_iter(&iter, ctx, &bytes_submitted); @@ -681,6 +709,15 @@ void iomap_readahead(const struct iomap_ops *ops, trace_iomap_readahead(rac->mapping->host, readahead_count(rac)); + /* + * Fetch fsverity_info for both data and fsverity metadata, as iomap + * needs zeroed hash for merkle tree block synthesis + */ + ctx->vi = fsverity_get_info(iter.inode); + if (ctx->vi && iter.pos < i_size_read(iter.inode)) + fsverity_readahead(ctx->vi, readahead_index(rac), + readahead_count(rac)); + while (iomap_iter(&iter, ops) > 0) iter.status = iomap_readahead_iter(&iter, ctx, &cur_bytes_submitted); diff --git a/fs/iomap/ioend.c b/fs/iomap/ioend.c index acf3cf98b23a..f7c3e0c70fd7 100644 --- a/fs/iomap/ioend.c +++ b/fs/iomap/ioend.c @@ -28,6 +28,7 @@ struct iomap_ioend *iomap_init_ioend(struct inode *inode, ioend->io_offset = file_offset; ioend->io_size = bio->bi_iter.bi_size; ioend->io_sector = bio->bi_iter.bi_sector; + ioend->io_vi = NULL; ioend->io_private = NULL; return ioend; } diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 5b2b40e81b61..1be2e16b696a 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -429,6 +429,7 @@ struct iomap_ioend { loff_t io_offset; /* offset in the file */ sector_t io_sector; /* start sector of ioend */ void *io_private; /* file system private data */ + struct fsverity_info *io_vi; /* fsverity info */ struct bio io_bio; /* MUST BE LAST! */ }; @@ -503,6 +504,7 @@ struct iomap_read_folio_ctx { struct readahead_control *rac; void *read_ctx; loff_t read_ctx_file_offset; + struct fsverity_info *vi; }; struct iomap_read_ops {