On 11/25, Eric Biggers wrote:
> From: Eric Biggers <ebigg...@google.com>
> 
> 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 <c...@kernel.org>
> Signed-off-by: Eric Biggers <ebigg...@google.com>
> ---
> 
> 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


_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

Reply via email to