btrfs: update SCRUB_MAX_PAGES_PER_BLOCK

Use BTRFS_MAX_METADATA_BLOCKSIZE and SZ_4K (minimal sectorsize) to
calculate this value.

And remove one stale comment on the value, in fact with recent subpage
support, BTRFS_MAX_METADATA_BLOCKSIZE * PAGE_SIZE is already beyond
BTRFS_STRIPE_LEN, just we don't use the full page.

Also since we're here, update the BUG_ON() related to
SCRUB_MAX_PAGES_PER_BLOCK to ASSERT().

As those ASSERT() are really only for developers to catch early obvious
bugs, not to let end users suffer.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 15a123e..0870d8d 100644 (file)
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -49,11 +49,10 @@ struct scrub_ctx;
 #define SCRUB_BIOS_PER_SCTX    64      /* 8MB per device in flight */
 
 /*
- * the following value times PAGE_SIZE needs to be large enough to match the
+ * The following value times PAGE_SIZE needs to be large enough to match the
  * largest node/leaf/sector size that shall be supported.
- * Values larger than BTRFS_STRIPE_LEN are not supported.
  */
-#define SCRUB_MAX_PAGES_PER_BLOCK      16      /* 64k per node/leaf/sector */
+#define SCRUB_MAX_PAGES_PER_BLOCK      (BTRFS_MAX_METADATA_BLOCKSIZE / SZ_4K)
 
 struct scrub_recover {
        refcount_t              refs;
@@ -1313,7 +1312,7 @@ static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
                recover->bioc = bioc;
                recover->map_length = mapped_length;
 
-               BUG_ON(page_index >= SCRUB_MAX_PAGES_PER_BLOCK);
+               ASSERT(page_index < SCRUB_MAX_PAGES_PER_BLOCK);
 
                nmirrors = min(scrub_nr_raid_mirrors(bioc), BTRFS_MAX_MIRRORS);
 
@@ -2297,7 +2296,7 @@ leave_nomem:
                        scrub_block_put(sblock);
                        return -ENOMEM;
                }
-               BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
+               ASSERT(index < SCRUB_MAX_PAGES_PER_BLOCK);
                scrub_page_get(spage);
                sblock->pagev[index] = spage;
                spage->sblock = sblock;
@@ -2631,7 +2630,7 @@ leave_nomem:
                        scrub_block_put(sblock);
                        return -ENOMEM;
                }
-               BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
+               ASSERT(index < SCRUB_MAX_PAGES_PER_BLOCK);
                /* For scrub block */
                scrub_page_get(spage);
                sblock->pagev[index] = spage;