On 11/25, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> 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 <chao@xxxxxxxxxx>
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> ---
>
> v4: Added a comment for decompression_attempted, added a paragraph to
> the commit message, and added Chao's Reviewed-by.
>
> v3: made a small simplification to the f2fs changes. Also dropped the
> fscrypt patch since it is upstream now.
>
> fs/ext4/readpage.c | 8 ++----
> fs/f2fs/compress.c | 64 ++++++++++++++++++++++------------------------
> fs/f2fs/data.c | 53 +++++++++++++++++++++++---------------
> fs/verity/verify.c | 12 ++++-----
> 4 files changed, 72 insertions(+), 65 deletions(-)
>
> diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
> index 3d21eae267fca..e604ea4e102b7 100644
> --- a/fs/ext4/readpage.c
> +++ b/fs/ext4/readpage.c
> @@ -75,14 +75,10 @@ static void __read_end_io(struct bio *bio)
> bio_for_each_segment_all(bv, bio, iter_all) {
> page = bv->bv_page;
>
> - /* PG_error was set if verity failed. */
> - if (bio->bi_status || PageError(page)) {
> + if (bio->bi_status)
> ClearPageUptodate(page);
> - /* will re-read again later */
> - ClearPageError(page);
> - } else {
> + else
> SetPageUptodate(page);
> - }
> unlock_page(page);
> }
> if (bio->bi_private)
> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> index d315c2de136f2..2b7a5cc4ed662 100644
> --- a/fs/f2fs/compress.c
> +++ b/fs/f2fs/compress.c
> @@ -1711,50 +1711,27 @@ static void f2fs_put_dic(struct decompress_io_ctx *dic, bool in_task)
> }
> }
>
> -/*
> - * Update and unlock the cluster's pagecache pages, and release the reference to
> - * the decompress_io_ctx that was being held for I/O completion.
> - */
> -static void __f2fs_decompress_end_io(struct decompress_io_ctx *dic, bool failed,
> - bool in_task)
> +static void f2fs_verify_cluster(struct work_struct *work)
> {
> + struct decompress_io_ctx *dic =
> + container_of(work, struct decompress_io_ctx, verity_work);
> int i;
>
> + /* Verify, update, and unlock the decompressed pages. */
> for (i = 0; i < dic->cluster_size; i++) {
> struct page *rpage = dic->rpages[i];
>
> if (!rpage)
> continue;
>
> - /* PG_error was set if verity failed. */
> - if (failed || PageError(rpage)) {
> - ClearPageUptodate(rpage);
> - /* will re-read again later */
> - ClearPageError(rpage);
> - } else {
> + if (fsverity_verify_page(rpage))
> SetPageUptodate(rpage);
> - }
> + else
> + ClearPageUptodate(rpage);
> unlock_page(rpage);
> }
>
> - f2fs_put_dic(dic, in_task);
> -}
> -
> -static void f2fs_verify_cluster(struct work_struct *work)
> -{
> - struct decompress_io_ctx *dic =
> - container_of(work, struct decompress_io_ctx, verity_work);
> - int i;
> -
> - /* Verify the cluster's decompressed pages with fs-verity. */
> - for (i = 0; i < dic->cluster_size; i++) {
> - struct page *rpage = dic->rpages[i];
> -
> - if (rpage && !fsverity_verify_page(rpage))
> - SetPageError(rpage);
> - }
> -
> - __f2fs_decompress_end_io(dic, false, true);
> + f2fs_put_dic(dic, true);
> }
>
> /*
> @@ -1764,6 +1741,8 @@ static void f2fs_verify_cluster(struct work_struct *work)
> void f2fs_decompress_end_io(struct decompress_io_ctx *dic, bool failed,
> bool in_task)
> {
> + int i;
> +
> if (!failed && dic->need_verity) {
> /*
> * Note that to avoid deadlocks, the verity work can't be done
> @@ -1773,9 +1752,28 @@ void f2fs_decompress_end_io(struct decompress_io_ctx *dic, bool failed,
> */
> INIT_WORK(&dic->verity_work, f2fs_verify_cluster);
> fsverity_enqueue_verify_work(&dic->verity_work);
> - } else {
> - __f2fs_decompress_end_io(dic, failed, in_task);
> + return;
> + }
> +
> + /* Update and unlock the cluster's pagecache pages. */
> + for (i = 0; i < dic->cluster_size; i++) {
> + struct page *rpage = dic->rpages[i];
> +
> + if (!rpage)
> + continue;
> +
> + if (failed)
> + ClearPageUptodate(rpage);
> + else
> + SetPageUptodate(rpage);
> + unlock_page(rpage);
> }
> +
> + /*
> + * Release the reference to the decompress_io_ctx that was being held
> + * for I/O completion.
> + */
> + f2fs_put_dic(dic, in_task);
> }
>
> /*
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index a71e818cd67b4..1ae8da259d6c5 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -116,43 +116,56 @@ struct bio_post_read_ctx {
> struct f2fs_sb_info *sbi;
> struct work_struct work;
> unsigned int enabled_steps;
> + /*
> + * decompression_attempted keeps track of whether
> + * f2fs_end_read_compressed_page() has been called on the pages in the
> + * bio that belong to a compressed cluster yet.
> + */
> + bool decompression_attempted;
> block_t fs_blkaddr;
> };
>
> +/*
> + * Update and unlock a bio's pages, and free the bio.
> + *
> + * This marks pages up-to-date only if there was no error in the bio (I/O error,
> + * decryption error, or verity error), as indicated by bio->bi_status.
> + *
> + * "Compressed pages" (pagecache pages backed by a compressed cluster on-disk)
> + * aren't marked up-to-date here, as decompression is done on a per-compression-
> + * cluster basis rather than a per-bio basis. Instead, we only must do two
> + * things for each compressed page here: call f2fs_end_read_compressed_page()
> + * with failed=true if an error occurred before it would have normally gotten
> + * called (i.e., I/O error or decryption error, but *not* verity error), and
> + * release the bio's reference to the decompress_io_ctx of the page's cluster.
> + */
> static void f2fs_finish_read_bio(struct bio *bio, bool in_task)
> {
> struct bio_vec *bv;
> struct bvec_iter_all iter_all;
> + struct bio_post_read_ctx *ctx = bio->bi_private;
>
> - /*
> - * Update and unlock the bio's pagecache pages, and put the
> - * decompression context for any compressed pages.
> - */
> bio_for_each_segment_all(bv, bio, iter_all) {
> struct page *page = bv->bv_page;
>
> if (f2fs_is_compressed_page(page)) {
> - if (bio->bi_status)
> + if (!ctx->decompression_attempted)
If seems this causes a panic due to the ctx nullified by f2fs_verify_bio.
> f2fs_end_read_compressed_page(page, true, 0,
> in_task);
> f2fs_put_page_dic(page, in_task);
> continue;
> }
>
> - /* PG_error was set if verity failed. */
> - if (bio->bi_status || PageError(page)) {
> + if (bio->bi_status)
> ClearPageUptodate(page);
> - /* will re-read again later */
> - ClearPageError(page);
> - } else {
> + else
> SetPageUptodate(page);
> - }
> dec_page_count(F2FS_P_SB(page), __read_io_type(page));
> unlock_page(page);
> }
>
> - if (bio->bi_private)
> - mempool_free(bio->bi_private, bio_post_read_ctx_pool);
> + if (ctx)
> + mempool_free(ctx, bio_post_read_ctx_pool);
> bio_put(bio);
> }
>
> @@ -185,8 +198,10 @@ static void f2fs_verify_bio(struct work_struct *work)
> struct page *page = bv->bv_page;
>
> if (!f2fs_is_compressed_page(page) &&
> - !fsverity_verify_page(page))
> - SetPageError(page);
> + !fsverity_verify_page(page)) {
> + bio->bi_status = BLK_STS_IOERR;
> + break;
> + }
> }
> } else {
> fsverity_verify_bio(bio);
> @@ -245,6 +260,8 @@ static void f2fs_handle_step_decompress(struct bio_post_read_ctx *ctx,
> blkaddr++;
> }
>
> + ctx->decompression_attempted = true;
> +
> /*
> * Optimization: if all the bio's pages are compressed, then scheduling
> * the per-bio verity work is unnecessary, as verity will be fully
> @@ -1062,6 +1079,7 @@ static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr,
> ctx->sbi = sbi;
> ctx->enabled_steps = post_read_steps;
> ctx->fs_blkaddr = blkaddr;
> + ctx->decompression_attempted = false;
> bio->bi_private = ctx;
> }
> iostat_alloc_and_bind_ctx(sbi, bio, ctx);
> @@ -1089,7 +1107,6 @@ static int f2fs_submit_page_read(struct inode *inode, struct page *page,
> bio_put(bio);
> return -EFAULT;
> }
> - ClearPageError(page);
> inc_page_count(sbi, F2FS_RD_DATA);
> f2fs_update_iostat(sbi, NULL, FS_DATA_READ_IO, F2FS_BLKSIZE);
> __submit_bio(sbi, bio, DATA);
> @@ -2141,7 +2158,6 @@ static int f2fs_read_single_page(struct inode *inode, struct page *page,
> inc_page_count(F2FS_I_SB(inode), F2FS_RD_DATA);
> f2fs_update_iostat(F2FS_I_SB(inode), NULL, FS_DATA_READ_IO,
> F2FS_BLKSIZE);
> - ClearPageError(page);
> *last_block_in_bio = block_nr;
> goto out;
> out:
> @@ -2289,7 +2305,6 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
>
> inc_page_count(sbi, F2FS_RD_DATA);
> f2fs_update_iostat(sbi, inode, FS_DATA_READ_IO, F2FS_BLKSIZE);
> - ClearPageError(page);
> *last_block_in_bio = blkaddr;
> }
>
> @@ -2306,7 +2321,6 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
> for (i = 0; i < cc->cluster_size; i++) {
> if (cc->rpages[i]) {
> ClearPageUptodate(cc->rpages[i]);
> - ClearPageError(cc->rpages[i]);
> unlock_page(cc->rpages[i]);
> }
> }
> @@ -2403,7 +2417,6 @@ static int f2fs_mpage_readpages(struct inode *inode,
> #ifdef CONFIG_F2FS_FS_COMPRESSION
> set_error_page:
> #endif
> - SetPageError(page);
> zero_user_segment(page, 0, PAGE_SIZE);
> unlock_page(page);
> }
> diff --git a/fs/verity/verify.c b/fs/verity/verify.c
> index bde8c9b7d25f6..961ba248021f9 100644
> --- a/fs/verity/verify.c
> +++ b/fs/verity/verify.c
> @@ -200,9 +200,8 @@ EXPORT_SYMBOL_GPL(fsverity_verify_page);
> * @bio: the bio to verify
> *
> * Verify a set of pages that have just been read from a verity file. The pages
> - * must be pagecache pages that are still locked and not yet uptodate. Pages
> - * that fail verification are set to the Error state. Verification is skipped
> - * for pages already in the Error state, e.g. due to fscrypt decryption failure.
> + * must be pagecache pages that are still locked and not yet uptodate. If a
> + * page fails verification, then bio->bi_status is set to an error status.
> *
> * This is a helper function for use by the ->readahead() method of filesystems
> * that issue bios to read data directly into the page cache. Filesystems that
> @@ -244,9 +243,10 @@ void fsverity_verify_bio(struct bio *bio)
> unsigned long level0_ra_pages =
> min(max_ra_pages, params->level0_blocks - level0_index);
>
> - if (!PageError(page) &&
> - !verify_page(inode, vi, req, page, level0_ra_pages))
> - SetPageError(page);
> + if (!verify_page(inode, vi, req, page, level0_ra_pages)) {
> + bio->bi_status = BLK_STS_IOERR;
> + break;
> + }
> }
>
> fsverity_free_hash_request(params->hash_alg, req);
>
> base-commit: f0c4d9fc9cc9462659728d168387191387e903cc
> --
> 2.38.1
