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authorJiro SEKIBA <jir@unicus.jp>2010-06-28 17:49:33 +0900
committerRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>2010-07-23 10:02:11 +0900
commitb2ac86e1a8e3a3b0ab4449d062c582f07a078e7b (patch)
treeb681ea820685a278e06995ff23b58f7a85904b70 /fs/nilfs2/the_nilfs.h
parentd26493b6f017c0b0063a15bf893411ddae85eee4 (diff)
downloadlinux-b2ac86e1a8e3a3b0ab4449d062c582f07a078e7b.tar.bz2
nilfs2: sync super blocks in turns
This will sync super blocks in turns instead of syncing duplicate super blocks at the time. This will help searching valid super root when super block is written into disk before log is written, which is happen when barrier-less block devices are unmounted uncleanly. In the situation, old super block likely points to valid log. This patch introduces ns_sbwcount member to the nilfs object and adds nilfs_sb_will_flip() function; ns_sbwcount counts how many times super blocks write back to the disk. And, nilfs_sb_will_flip() decides whether flipping required or not based on the count of ns_sbwcount to sync super blocks asymmetrically. The following functions are also changed: - nilfs_prepare_super(): flips super blocks according to the argument. The argument is calculated by nilfs_sb_will_flip() function. - nilfs_cleanup_super(): sets "clean" flag to both super blocks if they point to the same checkpoint. To update both of super block information, caller of nilfs_commit_super must set the information on both super blocks. Signed-off-by: Jiro SEKIBA <jir@unicus.jp> Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Diffstat (limited to 'fs/nilfs2/the_nilfs.h')
-rw-r--r--fs/nilfs2/the_nilfs.h17
1 files changed, 8 insertions, 9 deletions
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index 191560ec2e7f..32b4983b7458 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -57,7 +57,8 @@ enum {
* @ns_current: back pointer to current mount
* @ns_sbh: buffer heads of on-disk super blocks
* @ns_sbp: pointers to super block data
- * @ns_sbwtime: previous write time of super blocks
+ * @ns_sbwtime: previous write time of super block
+ * @ns_sbwcount: write count of super block
* @ns_sbsize: size of valid data in super block
* @ns_supers: list of nilfs super block structs
* @ns_seg_seq: segment sequence counter
@@ -119,7 +120,8 @@ struct the_nilfs {
*/
struct buffer_head *ns_sbh[2];
struct nilfs_super_block *ns_sbp[2];
- time_t ns_sbwtime[2];
+ time_t ns_sbwtime;
+ unsigned ns_sbwcount;
unsigned ns_sbsize;
unsigned ns_mount_state;
@@ -203,20 +205,17 @@ THE_NILFS_FNS(SB_DIRTY, sb_dirty)
/* Minimum interval of periodical update of superblocks (in seconds) */
#define NILFS_SB_FREQ 10
-#define NILFS_ALTSB_FREQ 60 /* spare superblock */
static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
{
u64 t = get_seconds();
- return t < nilfs->ns_sbwtime[0] ||
- t > nilfs->ns_sbwtime[0] + NILFS_SB_FREQ;
+ return t < nilfs->ns_sbwtime || t > nilfs->ns_sbwtime + NILFS_SB_FREQ;
}
-static inline int nilfs_altsb_need_update(struct the_nilfs *nilfs)
+static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs)
{
- u64 t = get_seconds();
- struct nilfs_super_block **sbp = nilfs->ns_sbp;
- return sbp[1] && t > nilfs->ns_sbwtime[1] + NILFS_ALTSB_FREQ;
+ int flip_bits = nilfs->ns_sbwcount & 0x0FL;
+ return (flip_bits != 0x08 && flip_bits != 0x0F);
}
void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);