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Subject[PATCH v2 2/7] f2fs: do in batches truncation in truncate_hole
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truncate_data_blocks_range can do in batches truncation which makes all
changes in dnode page content, dnode page status, extent cache, block
count updating together.

But previously, truncate_hole() always truncates one block in dnode page
at a time by invoking truncate_data_blocks_range(,1), which make thing
slow.

This patch changes truncate_hole() to do in batches truncation for all
target blocks in one direct node inside truncate_data_blocks_range, which
can make our punch hole operation in ->fallocate more efficent.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
---
v2:
changing slightly like below which is suggested by Jaegeuk:
o don't have to use index variable
o should not skip the entire dnode indices, when one of them is -ENOENT
fs/f2fs/file.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 27a789c..6702157 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -739,23 +739,31 @@ static int fill_zero(struct inode *inode, pgoff_t index,

int truncate_hole(struct inode *inode, pgoff_t pg_start, pgoff_t pg_end)
{
- pgoff_t index;
int err;

- for (index = pg_start; index < pg_end; index++) {
+ while (pg_start < pg_end) {
struct dnode_of_data dn;
+ pgoff_t end_offset, count;

set_new_dnode(&dn, inode, NULL, NULL, 0);
- err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
+ err = get_dnode_of_data(&dn, pg_start, LOOKUP_NODE);
if (err) {
- if (err == -ENOENT)
+ if (err == -ENOENT) {
+ pg_start++;
continue;
+ }
return err;
}

- if (dn.data_blkaddr != NULL_ADDR)
- truncate_data_blocks_range(&dn, 1);
+ end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));
+ count = min(end_offset - dn.ofs_in_node, pg_end - pg_start);
+
+ f2fs_bug_on(F2FS_I_SB(inode), count == 0 || count > end_offset);
+
+ truncate_data_blocks_range(&dn, count);
f2fs_put_dnode(&dn);
+
+ pg_start += count;
}
return 0;
}
--
2.5.2



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