From: Zhang Yi <yi.zhang@xxxxxxxxxx> After calling the ext4_da_map_blocks(), a delalloc extent state could be identified through the EXT4_MAP_DELAYED flag in map. So factor out buffer_head related handles in ext4_da_map_blocks(), make this function buffer_head unaware and becomes a common helper, and also update the stale function commtents, preparing for the iomap da write path in the future. Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> --- fs/ext4/inode.c | 63 ++++++++++++++++++++++++------------------------- 1 file changed, 31 insertions(+), 32 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 4febee4c833f..2afa3f83ddfb 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1749,36 +1749,32 @@ static int ext4_insert_delayed_blocks(struct inode *inode, ext4_lblk_t lblk, } /* - * This function is grabs code from the very beginning of - * ext4_map_blocks, but assumes that the caller is from delayed write - * time. This function looks up the requested blocks and sets the - * buffer delay bit under the protection of i_data_sem. + * Looks up the requested blocks and sets the delalloc extent map. + * First try to look up for the extent entry that contains the requested + * blocks in the extent status tree without i_data_sem, then try to look + * up for the ondisk extent mapping with i_data_sem in read mode, + * finally hold i_data_sem in write mode, looks up again and add a + * delalloc extent entry if it still couldn't find any extent. Pass out + * the mapped extent through @map and return 0 on success. */ -static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map, - struct buffer_head *bh) +static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map) { struct extent_status es; int retval; - sector_t invalid_block = ~((sector_t) 0xffff); #ifdef ES_AGGRESSIVE_TEST struct ext4_map_blocks orig_map; memcpy(&orig_map, map, sizeof(*map)); #endif - if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es)) - invalid_block = ~0; - map->m_flags = 0; ext_debug(inode, "max_blocks %u, logical block %lu\n", map->m_len, (unsigned long) map->m_lblk); /* Lookup extent status tree firstly */ if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) { - retval = es.es_len - (map->m_lblk - es.es_lblk); - if (retval > map->m_len) - retval = map->m_len; - map->m_len = retval; + map->m_len = min_t(unsigned int, map->m_len, + es.es_len - (map->m_lblk - es.es_lblk)); if (ext4_es_is_hole(&es)) goto add_delayed; @@ -1788,10 +1784,8 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map, * Delayed extent could be allocated by fallocate. * So we need to check it. */ - if (ext4_es_is_delayed(&es) && !ext4_es_is_unwritten(&es)) { - map_bh(bh, inode->i_sb, invalid_block); - set_buffer_new(bh); - set_buffer_delay(bh); + if (ext4_es_is_delonly(&es)) { + map->m_flags |= EXT4_MAP_DELAYED; return 0; } @@ -1806,7 +1800,7 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map, #ifdef ES_AGGRESSIVE_TEST ext4_map_blocks_es_recheck(NULL, inode, map, &orig_map, 0); #endif - return retval; + return 0; } /* @@ -1820,7 +1814,7 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map, retval = ext4_map_query_blocks(NULL, inode, map); up_read(&EXT4_I(inode)->i_data_sem); if (retval) - return retval; + return retval < 0 ? retval : 0; add_delayed: down_write(&EXT4_I(inode)->i_data_sem); @@ -1832,10 +1826,8 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map, * the extent status tree. */ if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) { - retval = es.es_len - (map->m_lblk - es.es_lblk); - if (retval > map->m_len) - retval = map->m_len; - map->m_len = retval; + map->m_len = min_t(unsigned int, map->m_len, + es.es_len - (map->m_lblk - es.es_lblk)); if (!ext4_es_is_hole(&es)) { up_write(&EXT4_I(inode)->i_data_sem); @@ -1845,18 +1837,14 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map, retval = ext4_map_query_blocks(NULL, inode, map); if (retval) { up_write(&EXT4_I(inode)->i_data_sem); - return retval; + return retval < 0 ? retval : 0; } } + map->m_flags |= EXT4_MAP_DELAYED; retval = ext4_insert_delayed_blocks(inode, map->m_lblk, map->m_len); up_write(&EXT4_I(inode)->i_data_sem); - if (retval) - return retval; - map_bh(bh, inode->i_sb, invalid_block); - set_buffer_new(bh); - set_buffer_delay(bh); return retval; } @@ -1876,11 +1864,15 @@ int ext4_da_get_block_prep(struct inode *inode, sector_t iblock, struct buffer_head *bh, int create) { struct ext4_map_blocks map; + sector_t invalid_block = ~((sector_t) 0xffff); int ret = 0; BUG_ON(create == 0); BUG_ON(bh->b_size != inode->i_sb->s_blocksize); + if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es)) + invalid_block = ~0; + map.m_lblk = iblock; map.m_len = 1; @@ -1889,10 +1881,17 @@ int ext4_da_get_block_prep(struct inode *inode, sector_t iblock, * preallocated blocks are unmapped but should treated * the same as allocated blocks. */ - ret = ext4_da_map_blocks(inode, &map, bh); - if (ret <= 0) + ret = ext4_da_map_blocks(inode, &map); + if (ret < 0) return ret; + if (map.m_flags & EXT4_MAP_DELAYED) { + map_bh(bh, inode->i_sb, invalid_block); + set_buffer_new(bh); + set_buffer_delay(bh); + return 0; + } + map_bh(bh, inode->i_sb, map.m_pblk); ext4_update_bh_state(bh, map.m_flags); -- 2.39.2