From: Nikolay Borisov Date: Wed, 2 May 2018 12:19:33 +0000 (+0300) Subject: btrfs: Factor out write portion of btrfs_get_blocks_direct X-Git-Tag: v4.18-rc1~176^2~4 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=c5794e51784a0a96dd82e8f955570a7eccf27e5d;p=linux.git btrfs: Factor out write portion of btrfs_get_blocks_direct Now that the read side is extracted into its own function, do the same to the write side. This leaves btrfs_get_blocks_direct_write with the sole purpose of handling common locking required. Also flip the condition in btrfs_get_blocks_direct_write so that the write case comes first and we check for if (Create) rather than if (!create). This is purely subjective but I believe makes reading a bit more "linear". No functional changes. Signed-off-by: Nikolay Borisov Signed-off-by: David Sterba --- diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 4f8fb1130cf3..880431ae5e59 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7561,6 +7561,104 @@ static int btrfs_get_blocks_direct_read(struct extent_map *em, return 0; } +static int btrfs_get_blocks_direct_write(struct extent_map **map, + struct buffer_head *bh_result, + struct inode *inode, + struct btrfs_dio_data *dio_data, + u64 start, u64 len) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + struct extent_map *em = *map; + int ret = 0; + + /* + * We don't allocate a new extent in the following cases + * + * 1) The inode is marked as NODATACOW. In this case we'll just use the + * existing extent. + * 2) The extent is marked as PREALLOC. We're good to go here and can + * just use the extent. + * + */ + if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags) || + ((BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) && + em->block_start != EXTENT_MAP_HOLE)) { + int type; + u64 block_start, orig_start, orig_block_len, ram_bytes; + + if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) + type = BTRFS_ORDERED_PREALLOC; + else + type = BTRFS_ORDERED_NOCOW; + len = min(len, em->len - (start - em->start)); + block_start = em->block_start + (start - em->start); + + if (can_nocow_extent(inode, start, &len, &orig_start, + &orig_block_len, &ram_bytes) == 1 && + btrfs_inc_nocow_writers(fs_info, block_start)) { + struct extent_map *em2; + + em2 = btrfs_create_dio_extent(inode, start, len, + orig_start, block_start, + len, orig_block_len, + ram_bytes, type); + btrfs_dec_nocow_writers(fs_info, block_start); + if (type == BTRFS_ORDERED_PREALLOC) { + free_extent_map(em); + *map = em = em2; + } + + if (em2 && IS_ERR(em2)) { + ret = PTR_ERR(em2); + goto out; + } + /* + * For inode marked NODATACOW or extent marked PREALLOC, + * use the existing or preallocated extent, so does not + * need to adjust btrfs_space_info's bytes_may_use. + */ + btrfs_free_reserved_data_space_noquota(inode, start, + len); + goto skip_cow; + } + } + + /* this will cow the extent */ + len = bh_result->b_size; + free_extent_map(em); + *map = em = btrfs_new_extent_direct(inode, start, len); + if (IS_ERR(em)) { + ret = PTR_ERR(em); + goto out; + } + + len = min(len, em->len - (start - em->start)); + +skip_cow: + 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); + + if (!test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) + set_buffer_new(bh_result); + + /* + * Need to update the i_size under the extent lock so buffered + * readers will get the updated i_size when we unlock. + */ + if (!dio_data->overwrite && start + len > i_size_read(inode)) + i_size_write(inode, start + len); + + WARN_ON(dio_data->reserve < len); + dio_data->reserve -= len; + dio_data->unsubmitted_oe_range_end = start + len; + current->journal_info = dio_data; +out: + return ret; +} + static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create) { @@ -7629,7 +7727,16 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock, goto unlock_err; } - if (!create) { + if (create) { + ret = btrfs_get_blocks_direct_write(&em, bh_result, inode, + dio_data, start, len); + if (ret < 0) + goto unlock_err; + + /* clear and unlock the entire range */ + clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart, lockend, + unlock_bits, 1, 0, &cached_state); + } else { ret = btrfs_get_blocks_direct_read(em, bh_result, inode, start, len); /* Can be negative only if we read from a hole */ @@ -7650,106 +7757,8 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock, } else { free_extent_state(cached_state); } - free_extent_map(em); - return 0; } - /* - * We don't allocate a new extent in the following cases - * - * 1) The inode is marked as NODATACOW. In this case we'll just use the - * existing extent. - * 2) The extent is marked as PREALLOC. We're good to go here and can - * just use the extent. - * - */ - if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags) || - ((BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) && - em->block_start != EXTENT_MAP_HOLE)) { - int type; - u64 block_start, orig_start, orig_block_len, ram_bytes; - - if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) - type = BTRFS_ORDERED_PREALLOC; - else - type = BTRFS_ORDERED_NOCOW; - len = min(len, em->len - (start - em->start)); - block_start = em->block_start + (start - em->start); - - if (can_nocow_extent(inode, start, &len, &orig_start, - &orig_block_len, &ram_bytes) == 1 && - btrfs_inc_nocow_writers(fs_info, block_start)) { - struct extent_map *em2; - - em2 = btrfs_create_dio_extent(inode, start, len, - orig_start, block_start, - len, orig_block_len, - ram_bytes, type); - btrfs_dec_nocow_writers(fs_info, block_start); - if (type == BTRFS_ORDERED_PREALLOC) { - free_extent_map(em); - em = em2; - } - if (em2 && IS_ERR(em2)) { - ret = PTR_ERR(em2); - goto unlock_err; - } - /* - * For inode marked NODATACOW or extent marked PREALLOC, - * use the existing or preallocated extent, so does not - * need to adjust btrfs_space_info's bytes_may_use. - */ - btrfs_free_reserved_data_space_noquota(inode, - start, len); - goto unlock; - } - } - - /* - * this will cow the extent, reset the len in case we changed - * it above - */ - len = bh_result->b_size; - free_extent_map(em); - em = btrfs_new_extent_direct(inode, start, len); - if (IS_ERR(em)) { - ret = PTR_ERR(em); - goto unlock_err; - } - len = min(len, em->len - (start - em->start)); -unlock: - 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); - if (create) { - if (!test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) - set_buffer_new(bh_result); - - /* - * Need to update the i_size under the extent lock so buffered - * readers will get the updated i_size when we unlock. - */ - if (!dio_data->overwrite && start + len > i_size_read(inode)) - i_size_write(inode, start + len); - - WARN_ON(dio_data->reserve < len); - dio_data->reserve -= len; - dio_data->unsubmitted_oe_range_end = start + len; - current->journal_info = dio_data; - } - - /* - * In the case of write we need to clear and unlock the entire range, - * in the case of read we need to unlock only the end area that we - * aren't using if there is any left over space. - */ - if (lockstart < lockend) { - clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart, - lockend, unlock_bits, 1, 0, - &cached_state); - } free_extent_map(em); return 0;