On 2022/8/16 7:50, 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.

Signed-off-by: Eric Biggers <ebigg...@google.com>
---
  fs/ext4/readpage.c |  8 ++----
  fs/f2fs/compress.c | 64 ++++++++++++++++++++++------------------------
  fs/f2fs/data.c     | 52 ++++++++++++++++++++-----------------
  fs/verity/verify.c | 12 ++++-----
  4 files changed, 68 insertions(+), 68 deletions(-)

diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
index 5ce4706f68a7c6..e604ea4e102b71 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 any post_read step 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 70e97075e535e5..f54fb3bb74197a 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1715,50 +1715,27 @@ 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);
  }
/*
@@ -1768,6 +1745,8 @@ 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
@@ -1777,9 +1756,28 @@ 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);

Will it be possible to clean up __f2fs_decompress_end_io() and
f2fs_verify_cluster(), they looks almost similar...

+               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 93cc2ec51c2aeb..34af260975a2e6 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -119,34 +119,41 @@ struct bio_post_read_ctx {
        block_t fs_blkaddr;
  };
-static void f2fs_finish_read_bio(struct bio *bio, bool in_task)
+/*
+ * 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,
+                                bool fail_compressed)

Not sure, fail_decompress or fail_decompression may looks more readable?

Thanks,

  {
        struct bio_vec *bv;
        struct bvec_iter_all iter_all;
- /*
-        * 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 (fail_compressed)
                                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);
        }
@@ -185,14 +192,17 @@ 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);
        }
- f2fs_finish_read_bio(bio, true);
+       f2fs_finish_read_bio(bio, true /* in_task */,
+                            false /* fail_compressed */);
  }
/*
@@ -212,7 +222,7 @@ static void f2fs_verify_and_finish_bio(struct bio *bio, 
bool in_task)
                INIT_WORK(&ctx->work, f2fs_verify_bio);
                fsverity_enqueue_verify_work(&ctx->work);
        } else {
-               f2fs_finish_read_bio(bio, in_task);
+               f2fs_finish_read_bio(bio, in_task, false /* fail_compressed */);
        }
  }
@@ -261,7 +271,8 @@ static void f2fs_post_read_work(struct work_struct *work)
        struct bio *bio = ctx->bio;
if ((ctx->enabled_steps & STEP_DECRYPT) && !fscrypt_decrypt_bio(bio)) {
-               f2fs_finish_read_bio(bio, true);
+               f2fs_finish_read_bio(bio, true /* in_task */,
+                                    true /* fail_compressed */);
                return;
        }
@@ -286,7 +297,7 @@ static void f2fs_read_end_io(struct bio *bio)
        }
if (bio->bi_status) {
-               f2fs_finish_read_bio(bio, intask);
+               f2fs_finish_read_bio(bio, intask, true /* fail_compressed */);
                return;
        }
@@ -1083,7 +1094,6 @@ 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, FS_DATA_READ_IO, F2FS_BLKSIZE);
        __submit_bio(sbi, bio, DATA);
@@ -2125,7 +2135,6 @@ 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), FS_DATA_READ_IO, F2FS_BLKSIZE);
-       ClearPageError(page);
        *last_block_in_bio = block_nr;
        goto out;
  out:
@@ -2274,7 +2283,6 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct 
bio **bio_ret,
                inc_page_count(sbi, F2FS_RD_DATA);
                f2fs_update_iostat(sbi, FS_DATA_READ_IO, F2FS_BLKSIZE);
                f2fs_update_iostat(sbi, FS_CDATA_READ_IO, F2FS_BLKSIZE);
-               ClearPageError(page);
                *last_block_in_bio = blkaddr;
        }
@@ -2291,7 +2299,6 @@ 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]);
                }
        }
@@ -2388,7 +2395,6 @@ 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 14e2fb49cff561..556dfbd4698dea 100644
--- a/fs/verity/verify.c
+++ b/fs/verity/verify.c
@@ -210,9 +210,8 @@ 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
@@ -254,9 +253,10 @@ 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);


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