From e861304b8ed83fe43e36d46794d72641c82d4636 Mon Sep 17 00:00:00 2001 From: Allison Henderson Date: Wed, 25 May 2011 07:41:46 -0400 Subject: [PATCH] ext4: add "punch hole" flag to ext4_map_blocks() This patch adds a new flag to ext4_map_blocks() that specifies the given range of blocks should be punched out. Extents are first converted to uninitialized extents before they are punched out. Because punching a hole may require that the extent be split, it is possible that the splitting may need more blocks than are available. To deal with this, use of reserved blocks are enabled to allow the split to proceed. The routine then returns the number of blocks successfully punched out. [ext4 punch hole patch series 4/5 v7] Signed-off-by: Allison Henderson Signed-off-by: "Theodore Ts'o" Reviewed-by: Mingming Cao --- fs/ext4/extents.c | 98 +++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 87 insertions(+), 11 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index c8c687b5d9a8..1d456b2ac377 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3298,15 +3298,19 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, ext4_fsblk_t newblock = 0; int err = 0, depth, ret; unsigned int allocated = 0; + unsigned int punched_out = 0; + unsigned int result = 0; struct ext4_allocation_request ar; ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio; + struct ext4_map_blocks punch_map; ext_debug("blocks %u/%u requested for inode %lu\n", map->m_lblk, map->m_len, inode->i_ino); trace_ext4_ext_map_blocks_enter(inode, map->m_lblk, map->m_len, flags); /* check in cache */ - if (ext4_ext_in_cache(inode, map->m_lblk, &newex)) { + if (ext4_ext_in_cache(inode, map->m_lblk, &newex) && + ((flags & EXT4_GET_BLOCKS_PUNCH_OUT_EXT) == 0)) { if (!newex.ee_start_lo && !newex.ee_start_hi) { if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) { /* @@ -3371,16 +3375,84 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, ext_debug("%u fit into %u:%d -> %llu\n", map->m_lblk, ee_block, ee_len, newblock); - /* Do not put uninitialized extent in the cache */ - if (!ext4_ext_is_uninitialized(ex)) { - ext4_ext_put_in_cache(inode, ee_block, - ee_len, ee_start); - goto out; + if ((flags & EXT4_GET_BLOCKS_PUNCH_OUT_EXT) == 0) { + /* + * Do not put uninitialized extent + * in the cache + */ + if (!ext4_ext_is_uninitialized(ex)) { + ext4_ext_put_in_cache(inode, ee_block, + ee_len, ee_start); + goto out; + } + ret = ext4_ext_handle_uninitialized_extents( + handle, inode, map, path, flags, + allocated, newblock); + return ret; } - ret = ext4_ext_handle_uninitialized_extents(handle, - inode, map, path, flags, allocated, - newblock); - return ret; + + /* + * Punch out the map length, but only to the + * end of the extent + */ + punched_out = allocated < map->m_len ? + allocated : map->m_len; + + /* + * Sense extents need to be converted to + * uninitialized, they must fit in an + * uninitialized extent + */ + if (punched_out > EXT_UNINIT_MAX_LEN) + punched_out = EXT_UNINIT_MAX_LEN; + + punch_map.m_lblk = map->m_lblk; + punch_map.m_pblk = newblock; + punch_map.m_len = punched_out; + punch_map.m_flags = 0; + + /* Check to see if the extent needs to be split */ + if (punch_map.m_len != ee_len || + punch_map.m_lblk != ee_block) { + + ret = ext4_split_extent(handle, inode, + path, &punch_map, 0, + EXT4_GET_BLOCKS_PUNCH_OUT_EXT | + EXT4_GET_BLOCKS_PRE_IO); + + if (ret < 0) { + err = ret; + goto out2; + } + /* + * find extent for the block at + * the start of the hole + */ + ext4_ext_drop_refs(path); + kfree(path); + + path = ext4_ext_find_extent(inode, + map->m_lblk, NULL); + if (IS_ERR(path)) { + err = PTR_ERR(path); + path = NULL; + goto out2; + } + + depth = ext_depth(inode); + ex = path[depth].p_ext; + ee_len = ext4_ext_get_actual_len(ex); + ee_block = le32_to_cpu(ex->ee_block); + ee_start = ext4_ext_pblock(ex); + + } + + ext4_ext_mark_uninitialized(ex); + + err = ext4_ext_remove_space(inode, map->m_lblk, + map->m_lblk + punched_out); + + goto out2; } } @@ -3525,7 +3597,11 @@ out2: } trace_ext4_ext_map_blocks_exit(inode, map->m_lblk, newblock, map->m_len, err ? err : allocated); - return err ? err : allocated; + + result = (flags & EXT4_GET_BLOCKS_PUNCH_OUT_EXT) ? + punched_out : allocated; + + return err ? err : result; } void ext4_ext_truncate(struct inode *inode) -- 2.30.2