Currently this function handles both the READ and WRITE dio cases. This is facilitated by a bunch of 'if' statements, a goto short-circuit statement and a very perverse aliasing of "!created"(READ) case by setting lockstart = lockend and checking for lockstart < lockend for detecting the write. Let's simplify this mess by extracting the READ-only code into a separate __btrfs_get_block_direct_read function. This is only the first step, the next one will be to factor out the write side as well. The end goal will be to have the common locking/ unlocking code in btrfs_get_blocks_direct and then it will call either the read|write subvariants. No functional changes.
Signed-off-by: Nikolay Borisov <nbori...@suse.com> --- fs/btrfs/inode.c | 49 ++++++++++++++++++++++++++++++++++++------------- 1 file changed, 36 insertions(+), 13 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 491a7397f6fa..fd99347d0c91 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7677,6 +7677,27 @@ static struct extent_map *create_io_em(struct inode *inode, u64 start, u64 len, return em; } + +static int __btrfs_get_blocks_direct_read(struct extent_map *em, + struct buffer_head *bh_result, + struct inode *inode, + u64 start, u64 len) +{ + if (em->block_start == EXTENT_MAP_HOLE || + test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) + return -ENOENT; + + len = min(len, em->len - (start - em->start)); + + bh_result->b_blocknr = (em->block_start + (start - em->start)) >> + inode->i_blkbits; + bh_result->b_size = len; + bh_result->b_bdev = em->bdev; + set_buffer_mapped(bh_result); + + return 0; +} + static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create) { @@ -7745,11 +7766,22 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock, goto unlock_err; } - /* Just a good old fashioned hole, return */ - if (!create && (em->block_start == EXTENT_MAP_HOLE || - test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) { + if (!create) { + ret = __btrfs_get_blocks_direct_read(em, bh_result, inode, + start, len); + /* Can be negative only if we read from a hole */ + if (ret < 0) { + ret = 0; + free_extent_map(em); + goto unlock_err; + } + /* + * We need to unlock only the end area that we aren't using + * if there is any leftover space + */ + free_extent_state(cached_state); free_extent_map(em); - goto unlock_err; + return 0; } /* @@ -7761,12 +7793,6 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock, * just use the extent. * */ - if (!create) { - len = min(len, em->len - (start - em->start)); - lockstart = start + len; - goto unlock; - } - if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags) || ((BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) && em->block_start != EXTENT_MAP_HOLE)) { @@ -7853,10 +7879,7 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock, clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart, lockend, unlock_bits, 1, 0, &cached_state); - } else { - free_extent_state(cached_state); } - free_extent_map(em); return 0; -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html