On Thu, Feb 22, 2018 at 06:12:13PM +0200, Nikolay Borisov wrote: > 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.
Reviewed-by: David Sterba <dste...@suse.com> uh what a convoluted code to untangle. A few style notes below. > > 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, Please drop the "__" the function is static and there's no underscore-less version. > + 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; Please add a separate label for that, the funcion uses the single exit block style (labels and one-or-two returns). > } > > /* > @@ -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; -- 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