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nilfs2: improve execution time of NILFS_IOCTL_GET_CPINFO ioctl

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The older a filesystem gets, the slower lscp command becomes.  This is
because nilfs_cpfile_do_get_cpinfo() function meets more hole blocks
as the start offset of valid checkpoint numbers gets bigger.

This reduces the overhead by skipping hole blocks efficiently with
nilfs_mdt_find_block() helper.

A measurement result of this patch is as follows:

Before:
$ time lscp
                 CNO        DATE     TIME  MODE  FLG      BLKCNT       ICNT
             5769303  2015-02-22 19:31:33   cp    -          108          1
             5769304  2015-02-22 19:38:54   cp    -          108          1

real    0m0.182s
user    0m0.003s
sys     0m0.180s

After:
$ time lscp
                 CNO        DATE     TIME  MODE  FLG      BLKCNT       ICNT
             5769303  2015-02-22 19:31:33   cp    -          108          1
             5769304  2015-02-22 19:38:54   cp    -          108          1

real    0m0.003s
user    0m0.001s
sys     0m0.002s

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ryusuke Konishi 2015-04-16 12:46:42 -07:00 committed by Linus Torvalds
parent fa33915c92
commit 53a2c3bdf4
1 changed files with 52 additions and 6 deletions
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58
fs/nilfs2/cpfile.c
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@ -53,6 +53,13 @@ nilfs_cpfile_get_offset(const struct inode *cpfile, __u64 cno)
return do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
}
static __u64 nilfs_cpfile_first_checkpoint_in_block(const struct inode *cpfile,
unsigned long blkoff)
{
return (__u64)nilfs_cpfile_checkpoints_per_block(cpfile) * blkoff
+ 1 - NILFS_MDT(cpfile)->mi_first_entry_offset;
}
static unsigned long
nilfs_cpfile_checkpoints_in_block(const struct inode *cpfile,
__u64 curr,
@ -146,6 +153,44 @@ static inline int nilfs_cpfile_get_checkpoint_block(struct inode *cpfile,
create, nilfs_cpfile_block_init, bhp);
}
/**
* nilfs_cpfile_find_checkpoint_block - find and get a buffer on cpfile
* @cpfile: inode of cpfile
* @start_cno: start checkpoint number (inclusive)
* @end_cno: end checkpoint number (inclusive)
* @cnop: place to store the next checkpoint number
* @bhp: place to store a pointer to buffer_head struct
*
* Return Value: On success, it returns 0. On error, the following negative
* error code is returned.
*
* %-ENOMEM - Insufficient memory available.
*
* %-EIO - I/O error
*
* %-ENOENT - no block exists in the range.
*/
static int nilfs_cpfile_find_checkpoint_block(struct inode *cpfile,
__u64 start_cno, __u64 end_cno,
__u64 *cnop,
struct buffer_head **bhp)
{
unsigned long start, end, blkoff;
int ret;
if (unlikely(start_cno > end_cno))
return -ENOENT;
start = nilfs_cpfile_get_blkoff(cpfile, start_cno);
end = nilfs_cpfile_get_blkoff(cpfile, end_cno);
ret = nilfs_mdt_find_block(cpfile, start, end, &blkoff, bhp);
if (!ret)
*cnop = (blkoff == start) ? start_cno :
nilfs_cpfile_first_checkpoint_in_block(cpfile, blkoff);
return ret;
}
static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,
__u64 cno)
{
@ -403,14 +448,15 @@ static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
return -ENOENT; /* checkpoint number 0 is invalid */
down_read(&NILFS_MDT(cpfile)->mi_sem);
for (n = 0; cno < cur_cno && n < nci; cno += ncps) {
ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
for (n = 0; n < nci; cno += ncps) {
ret = nilfs_cpfile_find_checkpoint_block(
cpfile, cno, cur_cno - 1, &cno, &bh);
if (ret < 0) {
if (ret != -ENOENT)
goto out;
continue; /* skip hole */
if (likely(ret == -ENOENT))
break;
goto out;
}
ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
kaddr = kmap_atomic(bh->b_page);
cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);