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Message-ID: <20141121145725.GD30246@wallace>
Date: Fri, 21 Nov 2014 09:57:25 -0500
From: Eric Whitney <enwlinux@...il.com>
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu
Subject: [PATCH 3/4] 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 <enwlinux@...il.com>
---
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",
--
1.9.1
--
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