btrfs: zoned: don't clear dirty flag of extent buffer

One a zoned filesystem, never clear the dirty flag of an extent buffer,
but instead mark it as zeroout.

On writeout, when encountering a marked extent_buffer, zero it out.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 21c7835b46eca47a76fe35ee56fd3e0045946c6e..7b55b59115e7f110ac4915abfee14d0875f72103 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -254,8 +254,13 @@ blk_status_t btree_csum_one_bio(struct btrfs_bio *bbio)
        if (WARN_ON_ONCE(bbio->bio.bi_iter.bi_size != eb->len))
                return BLK_STS_IOERR;
 
+       /*
+        * If an extent_buffer is marked as EXTENT_BUFFER_ZONED_ZEROOUT, don't
+        * checksum it but zero-out its content. This is done to preserve
+        * ordering of I/O without unnecessarily writing out data.
+        */
        if (test_bit(EXTENT_BUFFER_ZONED_ZEROOUT, &eb->bflags)) {
-               WARN_ON_ONCE(found_start != 0);
+               memzero_extent_buffer(eb, 0, eb->len);
                return BLK_STS_OK;
        }
 

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 85cee54200ce41bcb3273dd373f3c16a6a01b09f..671010de7964b45bba2df7a0f92aadd13ff4a2a2 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3761,6 +3761,20 @@ void btrfs_clear_buffer_dirty(struct btrfs_trans_handle *trans,
        if (trans && btrfs_header_generation(eb) != trans->transid)
                return;
 
+       /*
+        * Instead of clearing the dirty flag off of the buffer, mark it as
+        * EXTENT_BUFFER_ZONED_ZEROOUT. This allows us to preserve
+        * write-ordering in zoned mode, without the need to later re-dirty
+        * the extent_buffer.
+        *
+        * The actual zeroout of the buffer will happen later in
+        * btree_csum_one_bio.
+        */
+       if (btrfs_is_zoned(fs_info)) {
+               set_bit(EXTENT_BUFFER_ZONED_ZEROOUT, &eb->bflags);
+               return;
+       }
+
        if (!test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags))
                return;
 
@@ -4152,8 +4166,6 @@ static void __write_extent_buffer(const struct extent_buffer *eb,
        /* For unmapped (dummy) ebs, no need to check their uptodate status. */
        const bool check_uptodate = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);
 
-       WARN_ON(test_bit(EXTENT_BUFFER_ZONED_ZEROOUT, &eb->bflags));
-
        if (check_eb_range(eb, start, len))
                return;
 

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index f1bcf2ac618011e027b2a047300ff7f0e0ae43f2..2c7fe6699cf4ec1a705a1ade421cc6a10d8ab52b 100644 (file)
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1713,7 +1713,8 @@ void btrfs_redirty_list_add(struct btrfs_transaction *trans,
            btrfs_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN))
                return;
 
-       ASSERT(!test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
+       ASSERT(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
+       ASSERT(test_bit(EXTENT_BUFFER_ZONED_ZEROOUT, &eb->bflags));
 
        memzero_extent_buffer(eb, 0, eb->len);
        set_bit(EXTENT_BUFFER_ZONED_ZEROOUT, &eb->bflags);