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Commit 53a2c3bd authored by Ryusuke Konishi's avatar Ryusuke Konishi Committed by Linus Torvalds
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nilfs2: improve execution time of NILFS_IOCTL_GET_CPINFO ioctl 



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: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent fa33915c

fs/nilfs2/cpfile.c

+52 −6
Original line number Original line Diff line number Diff line
@@ -53,6 +53,13 @@ nilfs_cpfile_get_offset(const struct inode *cpfile, __u64 cno) 
	return do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));

	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

static unsigned long

nilfs_cpfile_checkpoints_in_block(const struct inode *cpfile,

nilfs_cpfile_checkpoints_in_block(const struct inode *cpfile,

				  __u64 curr,

				  __u64 curr,
@@ -146,6 +153,44 @@ static inline int nilfs_cpfile_get_checkpoint_block(struct inode *cpfile, 
				   create, nilfs_cpfile_block_init, bhp);

				   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,

static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,

						       __u64 cno)

						       __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 */

		return -ENOENT; /* checkpoint number 0 is invalid */

	down_read(&NILFS_MDT(cpfile)->mi_sem);

	down_read(&NILFS_MDT(cpfile)->mi_sem);





	for (n = 0; cno < cur_cno && n < nci; cno += ncps) {

	for (n = 0; n < nci; cno += ncps) {

		ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);

		ret = nilfs_cpfile_find_checkpoint_block(

		ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);

			cpfile, cno, cur_cno - 1, &cno, &bh);

		if (ret < 0) {

		if (ret < 0) {

			if (ret != -ENOENT)

			if (likely(ret == -ENOENT))

				break;

			goto out;

			goto out;

			continue; /* skip hole */

		}

		}

		ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);





		kaddr = kmap_atomic(bh->b_page);

		kaddr = kmap_atomic(bh->b_page);

		cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);

		cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);