From 345ee947482f1c787b31014008586b8f512af1bd Mon Sep 17 00:00:00 2001 From: Eric Whitney Date: Sun, 23 Nov 2014 00:59:39 -0500 Subject: [PATCH] ext4: miscellaneous partial cluster cleanups Add some casts and rearrange a few statements for improved readability. Some code can also be simplified and made more readable if we set partial_cluster to 0 rather than to a negative value when we can tell we've hit the left edge of the punched region. Signed-off-by: Eric Whitney Signed-off-by: Theodore Ts'o --- fs/ext4/extents.c | 39 +++++++++++++++++++++------------------ 1 file changed, 21 insertions(+), 18 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 859ab37..841adf0 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -2481,7 +2481,7 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode, ext4_lblk_t from, ext4_lblk_t to) { struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); - unsigned short ee_len = ext4_ext_get_actual_len(ex); + unsigned short ee_len = ext4_ext_get_actual_len(ex); ext4_fsblk_t pblk; int flags = get_default_free_blocks_flags(inode); @@ -2490,7 +2490,7 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode, * at the beginning of the extent. Instead, we make a note * that we tried freeing the cluster, and check to see if we * need to free it on a subsequent call to ext4_remove_blocks, - * or at the end of the ext4_truncate() operation. + * or at the end of ext4_ext_rm_leaf or ext4_ext_remove_space. */ flags |= EXT4_FREE_BLOCKS_NOFREE_FIRST_CLUSTER; @@ -2501,8 +2501,8 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode, * partial cluster here. */ pblk = ext4_ext_pblock(ex) + ee_len - 1; - if ((*partial_cluster > 0) && - (EXT4_B2C(sbi, pblk) != *partial_cluster)) { + if (*partial_cluster > 0 && + *partial_cluster != (long long) EXT4_B2C(sbi, pblk)) { ext4_free_blocks(handle, inode, NULL, EXT4_C2B(sbi, *partial_cluster), sbi->s_cluster_ratio, flags); @@ -2528,7 +2528,7 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode, && to == le32_to_cpu(ex->ee_block) + ee_len - 1) { /* tail removal */ ext4_lblk_t num; - unsigned int unaligned; + long long first_cluster; num = le32_to_cpu(ex->ee_block) + ee_len - from; pblk = ext4_ext_pblock(ex) + ee_len - num; @@ -2538,7 +2538,7 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode, * used by any other extent (partial_cluster is negative). */ if (*partial_cluster < 0 && - -(*partial_cluster) == EXT4_B2C(sbi, pblk + num - 1)) + *partial_cluster == -(long long) EXT4_B2C(sbi, pblk+num-1)) flags |= EXT4_FREE_BLOCKS_NOFREE_LAST_CLUSTER; ext_debug("free last %u blocks starting %llu partial %lld\n", @@ -2549,21 +2549,24 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode, * beginning of a cluster, and we removed the entire * extent and the cluster is not used by any other extent, * save the partial cluster here, since we might need to - * delete if we determine that the truncate operation has - * removed all of the blocks in the cluster. + * delete if we determine that the truncate or punch hole + * operation has removed all of the blocks in the cluster. + * If that cluster is used by another extent, preserve its + * negative value so it isn't freed later on. * - * On the other hand, if we did not manage to free the whole - * extent, we have to mark the cluster as used (store negative - * cluster number in partial_cluster). + * If the whole extent wasn't freed, we've reached the + * start of the truncated/punched region and have finished + * removing blocks. If there's a partial cluster here it's + * shared with the remainder of the extent and is no longer + * a candidate for removal. */ - unaligned = EXT4_PBLK_COFF(sbi, pblk); - if (unaligned && (ee_len == num) && - (*partial_cluster != -((long long)EXT4_B2C(sbi, pblk)))) - *partial_cluster = EXT4_B2C(sbi, pblk); - else if (unaligned) - *partial_cluster = -((long long)EXT4_B2C(sbi, pblk)); - else if (*partial_cluster > 0) + if (EXT4_PBLK_COFF(sbi, pblk) && ee_len == num) { + first_cluster = (long long) EXT4_B2C(sbi, pblk); + if (first_cluster != -*partial_cluster) + *partial_cluster = first_cluster; + } else { *partial_cluster = 0; + } } else ext4_error(sbi->s_sb, "strange request: removal(2) " "%u-%u from %u:%u\n", -- 2.7.4