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nilfs2: apply readahead for recovery on mount

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This inserts readahead in the recovery code.  The readahead request is
issued per segment while searching the latest super root block.

This will shorten mount time after unclean unmount.  A measurement
shows the recovery time was reduced by more than 60 percent:

 e.g. real  0m11.586s -> 0m3.918s  (x 2.96)

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
This commit is contained in:
Ryusuke Konishi 2009-11-19 22:24:48 +09:00
parent f021759d74
commit 050b4142c9
1 changed files with 19 additions and 7 deletions
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26
fs/nilfs2/recovery.c
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@ -798,6 +798,7 @@ int nilfs_search_super_root(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi,
struct nilfs_segsum_info ssi;
sector_t pseg_start, pseg_end, sr_pseg_start = 0;
sector_t seg_start, seg_end; /* range of full segment (block number) */
sector_t b, end;
u64 seg_seq;
__u64 segnum, nextnum = 0;
__u64 cno;
@ -813,6 +814,11 @@ int nilfs_search_super_root(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi,
/* Calculate range of segment */
nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
/* Read ahead segment */
b = seg_start;
while (b <= seg_end)
sb_breadahead(sbi->s_super, b++);
for (;;) {
/* Load segment summary */
ret = load_segment_summary(sbi, pseg_start, seg_seq, &ssi, 1);
@ -835,14 +841,20 @@ int nilfs_search_super_root(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi,
ri->ri_nextnum = nextnum;
empty_seg = 0;
if (!NILFS_SEG_HAS_SR(&ssi) && !scan_newer) {
/* This will never happen because a superblock
(last_segment) always points to a pseg
having a super root. */
ret = NILFS_SEG_FAIL_CONSISTENCY;
goto failed;
}
if (pseg_start == seg_start) {
nilfs_get_segment_range(nilfs, nextnum, &b, &end);
while (b <= end)
sb_breadahead(sbi->s_super, b++);
}
if (!NILFS_SEG_HAS_SR(&ssi)) {
if (!scan_newer) {
/* This will never happen because a superblock
(last_segment) always points to a pseg
having a super root. */
ret = NILFS_SEG_FAIL_CONSISTENCY;
goto failed;
}
if (!ri->ri_lsegs_start && NILFS_SEG_LOGBGN(&ssi)) {
ri->ri_lsegs_start = pseg_start;
ri->ri_lsegs_start_seq = seg_seq;