[f2fs-dev] [PATCH v11 05/20] fsverity: improve flushing performance of fsverity_fill_zerohash
Andrey Albershteyn via Linux-f2fs-devel <[email protected]>
| Newsgroups | net.sourceforge.lists.linux-f2fs-devel,dev.linux.lists.fsverity,org.kernel.vger.linux-btrfs,org.kernel.vger.linux-ext4,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-xfs |
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| Message-ID | <[email protected]> |
The current version calls flush_dcache_folio(), in memcpy_to_folio(), to flush whole folio on every digest (which is 128 for 4k). Open code folio mapping and flushing to copy all digests at once. Reported-by: Eric Biggers <[email protected]> Link: https://lore.kernel.org/linux-fsdevel/20260401222717.GH2466@quark/ Signed-off-by: Andrey Albershteyn <[email protected]> --- fs/verity/pagecache.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) diff --git a/fs/verity/pagecache.c b/fs/verity/pagecache.c index 9d82e6b74ba1..270abd652e48 100644 --- a/fs/verity/pagecache.c +++ b/fs/verity/pagecache.c @@ -68,14 +68,32 @@ EXPORT_SYMBOL_GPL(generic_readahead_merkle_tree); void fsverity_fill_zerohash(struct folio *folio, size_t offset, size_t len, struct fsverity_info *vi) { - size_t off = offset; + void *vaddr; + void *to; + size_t chunk; WARN_ON_ONCE(!IS_ALIGNED(offset, vi->tree_params.digest_size)); WARN_ON_ONCE(!IS_ALIGNED(len, vi->tree_params.digest_size)); + WARN_ON_ONCE(offset + len > folio_size(folio)); - for (; off < (offset + len); off += vi->tree_params.digest_size) - memcpy_to_folio(folio, off, vi->tree_params.zero_digest, + do { + vaddr = kmap_local_folio(folio, offset); + chunk = len; + to = vaddr; + + if (folio_test_partial_kmap(folio) && + chunk > PAGE_SIZE - offset_in_page(offset)) + chunk = PAGE_SIZE - offset_in_page(offset); + for (; to < (vaddr + chunk); to += vi->tree_params.digest_size) + memcpy(to, vi->tree_params.zero_digest, vi->tree_params.digest_size); + kunmap_local(vaddr); + + offset += chunk; + len -= chunk; + } while (len > 0); + + flush_dcache_folio(folio); } EXPORT_SYMBOL_GPL(fsverity_fill_zerohash); -- 2.54.0 _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel