btrfs: stash ordered extent in dio_data during iomap dio

While it is not feasible for an ordered extent to survive across the
calls btrfs_direct_write makes into __iomap_dio_rw, it is still helpful
to stash it on the dio_data in between creating it in iomap_begin and
finishing it in either end_io or iomap_end.

The specific use I have in mind is that we can check if a particular bio
is partial in submit_io without unconditionally looking up the ordered
extent. This is a preparatory patch for a later patch which does just
that.

Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 865d56ff2ce150476ee12b34829781a8f5d78658..640cbd5a23deb2921536a3dcc14979246e1725a1 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -79,6 +79,7 @@ struct btrfs_iget_args {
 struct btrfs_dio_data {
        ssize_t submitted;
        struct extent_changeset *data_reserved;
+       struct btrfs_ordered_extent *ordered;
        bool data_space_reserved;
        bool nocow_done;
 };
@@ -6965,6 +6966,7 @@ out:
 }
 
 static struct extent_map *btrfs_create_dio_extent(struct btrfs_inode *inode,
+                                                 struct btrfs_dio_data *dio_data,
                                                  const u64 start,
                                                  const u64 len,
                                                  const u64 orig_start,
@@ -6975,7 +6977,7 @@ static struct extent_map *btrfs_create_dio_extent(struct btrfs_inode *inode,
                                                  const int type)
 {
        struct extent_map *em = NULL;
-       int ret;
+       struct btrfs_ordered_extent *ordered;
 
        if (type != BTRFS_ORDERED_NOCOW) {
                em = create_io_em(inode, start, len, orig_start, block_start,
@@ -6985,18 +6987,21 @@ static struct extent_map *btrfs_create_dio_extent(struct btrfs_inode *inode,
                if (IS_ERR(em))
                        goto out;
        }
-       ret = btrfs_add_ordered_extent(inode, start, len, len, block_start,
-                                      block_len, 0,
-                                      (1 << type) |
-                                      (1 << BTRFS_ORDERED_DIRECT),
-                                      BTRFS_COMPRESS_NONE);
-       if (ret) {
+       ordered = btrfs_alloc_ordered_extent(inode, start, len, len,
+                                            block_start, block_len, 0,
+                                            (1 << type) |
+                                            (1 << BTRFS_ORDERED_DIRECT),
+                                            BTRFS_COMPRESS_NONE);
+       if (IS_ERR(ordered)) {
                if (em) {
                        free_extent_map(em);
                        btrfs_drop_extent_map_range(inode, start,
                                                    start + len - 1, false);
                }
-               em = ERR_PTR(ret);
+               em = ERR_CAST(ordered);
+       } else {
+               ASSERT(!dio_data->ordered);
+               dio_data->ordered = ordered;
        }
  out:
 
@@ -7004,6 +7009,7 @@ static struct extent_map *btrfs_create_dio_extent(struct btrfs_inode *inode,
 }
 
 static struct extent_map *btrfs_new_extent_direct(struct btrfs_inode *inode,
+                                                 struct btrfs_dio_data *dio_data,
                                                  u64 start, u64 len)
 {
        struct btrfs_root *root = inode->root;
@@ -7019,7 +7025,7 @@ static struct extent_map *btrfs_new_extent_direct(struct btrfs_inode *inode,
        if (ret)
                return ERR_PTR(ret);
 
-       em = btrfs_create_dio_extent(inode, start, ins.offset, start,
+       em = btrfs_create_dio_extent(inode, dio_data, start, ins.offset, start,
                                     ins.objectid, ins.offset, ins.offset,
                                     ins.offset, BTRFS_ORDERED_REGULAR);
        btrfs_dec_block_group_reservations(fs_info, ins.objectid);
@@ -7364,7 +7370,7 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
                }
                space_reserved = true;
 
-               em2 = btrfs_create_dio_extent(BTRFS_I(inode), start, len,
+               em2 = btrfs_create_dio_extent(BTRFS_I(inode), dio_data, start, len,
                                              orig_start, block_start,
                                              len, orig_block_len,
                                              ram_bytes, type);
@@ -7406,7 +7412,7 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
                        goto out;
                space_reserved = true;
 
-               em = btrfs_new_extent_direct(BTRFS_I(inode), start, len);
+               em = btrfs_new_extent_direct(BTRFS_I(inode), dio_data, start, len);
                if (IS_ERR(em)) {
                        ret = PTR_ERR(em);
                        goto out;
@@ -7712,6 +7718,10 @@ static int btrfs_dio_iomap_end(struct inode *inode, loff_t pos, loff_t length,
                                      pos + length - 1, NULL);
                ret = -ENOTBLK;
        }
+       if (write) {
+               btrfs_put_ordered_extent(dio_data->ordered);
+               dio_data->ordered = NULL;
+       }
 
        if (write)
                extent_changeset_free(dio_data->data_reserved);
@@ -7773,7 +7783,7 @@ static const struct iomap_dio_ops btrfs_dio_ops = {
 
 ssize_t btrfs_dio_read(struct kiocb *iocb, struct iov_iter *iter, size_t done_before)
 {
-       struct btrfs_dio_data data;
+       struct btrfs_dio_data data = { 0 };
 
        return iomap_dio_rw(iocb, iter, &btrfs_dio_iomap_ops, &btrfs_dio_ops,
                            IOMAP_DIO_PARTIAL, &data, done_before);
@@ -7782,7 +7792,7 @@ ssize_t btrfs_dio_read(struct kiocb *iocb, struct iov_iter *iter, size_t done_be
 struct iomap_dio *btrfs_dio_write(struct kiocb *iocb, struct iov_iter *iter,
                                  size_t done_before)
 {
-       struct btrfs_dio_data data;
+       struct btrfs_dio_data data = { 0 };
 
        return __iomap_dio_rw(iocb, iter, &btrfs_dio_iomap_ops, &btrfs_dio_ops,
                            IOMAP_DIO_PARTIAL, &data, done_before);