Hi, thank you for the comments.
At Fri, 25 Jun 2010 18:06:39 +0900 (JST),
Ryusuke Konishi wrote:
>
> On Fri, 25 Jun 2010 00:27:40 +0900, Jiro SEKIBA wrote:
> > 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, which counts how many times super
> > blocks write back to the disk. Newly introduced nilfs_sb_need_swap() function
> > decides whether flipping required or not based on the ns_sbwcount to sync
> > super blocks asymmetrically.
> >
> > nilfs_prepare_super swaps super blocks according to the argument.
> > The argument is calculated by nilfs_sb_need_swap() function.
> >
> > The patch also introduces new function nilfs_set_log_cursor to advance
> > log cursor for specified super block. 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@xxxxxxxxx>
>
> May I change the function name of "nilfs_sb_need_swap" to
> "nilfs_sb_will_flip" or something?
>
> "need swap" looks confusing at first glance.
OK, I'll change it nilfs_sb_will_flip.
if you have any further comments, please let me know
thanks,
regards,
> Regards,
> Ryusuke Konishi
>
> > ---
> > fs/nilfs2/nilfs.h | 13 +++++-
> > fs/nilfs2/segment.c | 10 +++-
> > fs/nilfs2/super.c | 131 ++++++++++++++++++++++++++++++++-----------------
> > fs/nilfs2/the_nilfs.c | 10 ++--
> > fs/nilfs2/the_nilfs.h | 17 +++---
> > 5 files changed, 119 insertions(+), 62 deletions(-)
> >
> > diff --git a/fs/nilfs2/nilfs.h b/fs/nilfs2/nilfs.h
> > index 649e079..63c8fd4 100644
> > --- a/fs/nilfs2/nilfs.h
> > +++ b/fs/nilfs2/nilfs.h
> > @@ -107,6 +107,14 @@ enum {
> > };
> >
> > /*
> > + * commit flags for nilfs_commit_super and nilfs_sync_super
> > + */
> > +enum {
> > + NILFS_SB_COMMIT = 0, /* Commit a super block alternately */
> > + NILFS_SB_COMMIT_ALL /* Commit both super blocks */
> > +};
> > +
> > +/*
> > * Macros to check inode numbers
> > */
> > #define NILFS_MDT_INO_BITS \
> > @@ -270,7 +278,10 @@ extern struct nilfs_super_block *
> > nilfs_read_super_block(struct super_block *, u64, int, struct buffer_head **);
> > extern int nilfs_store_magic_and_option(struct super_block *,
> > struct nilfs_super_block *, char *);
> > -extern struct nilfs_super_block **nilfs_prepare_super(struct nilfs_sb_info *);
> > +extern void nilfs_set_log_cursor(struct nilfs_super_block *,
> > + struct the_nilfs *);
> > +extern struct nilfs_super_block **nilfs_prepare_super(struct nilfs_sb_info *,
> > + int flip);
> > extern int nilfs_commit_super(struct nilfs_sb_info *, int);
> > extern int nilfs_attach_checkpoint(struct nilfs_sb_info *, __u64);
> > extern void nilfs_detach_checkpoint(struct nilfs_sb_info *);
> > diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
> > index 075d7b0..844743e 100644
> > --- a/fs/nilfs2/segment.c
> > +++ b/fs/nilfs2/segment.c
> > @@ -2408,6 +2408,7 @@ static int nilfs_segctor_construct(struct nilfs_sc_info *sci, int mode)
> > {
> > struct nilfs_sb_info *sbi = sci->sc_sbi;
> > struct the_nilfs *nilfs = sbi->s_nilfs;
> > + struct nilfs_super_block **sbp;
> > int err = 0;
> >
> > nilfs_segctor_accept(sci);
> > @@ -2424,9 +2425,12 @@ static int nilfs_segctor_construct(struct nilfs_sc_info *sci, int mode)
> > nilfs_discontinued(nilfs)) {
> > down_write(&nilfs->ns_sem);
> > err = -EIO;
> > - if (likely(nilfs_prepare_super(sbi)))
> > - err = nilfs_commit_super(
> > - sbi, nilfs_altsb_need_update(nilfs));
> > + sbp = nilfs_prepare_super(sbi,
> > + nilfs_sb_need_swap(nilfs));
> > + if (likely(sbp)) {
> > + nilfs_set_log_cursor(sbp[0], nilfs);
> > + err = nilfs_commit_super(sbi, NILFS_SB_COMMIT);
> > + }
> > up_write(&nilfs->ns_sem);
> > }
> > }
> > diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
> > index 045b8d7..cd35f73 100644
> > --- a/fs/nilfs2/super.c
> > +++ b/fs/nilfs2/super.c
> > @@ -74,6 +74,25 @@ struct kmem_cache *nilfs_btree_path_cache;
> >
> > static int nilfs_remount(struct super_block *sb, int *flags, char *data);
> >
> > +static void nilfs_set_error(struct nilfs_sb_info *sbi)
> > +{
> > + struct the_nilfs *nilfs = sbi->s_nilfs;
> > + struct nilfs_super_block **sbp;
> > +
> > + down_write(&nilfs->ns_sem);
> > + if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
> > + nilfs->ns_mount_state |= NILFS_ERROR_FS;
> > + sbp = nilfs_prepare_super(sbi, 0);
> > + if (likely(sbp)) {
> > + sbp[0]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
> > + if (sbp[1])
> > + sbp[1]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
> > + nilfs_commit_super(sbi, NILFS_SB_COMMIT_ALL);
> > + }
> > + }
> > + up_write(&nilfs->ns_sem);
> > +}
> > +
> > /**
> > * nilfs_error() - report failure condition on a filesystem
> > *
> > @@ -90,7 +109,6 @@ void nilfs_error(struct super_block *sb, const char *function,
> > const char *fmt, ...)
> > {
> > struct nilfs_sb_info *sbi = NILFS_SB(sb);
> > - struct nilfs_super_block **sbp;
> > va_list args;
> >
> > va_start(args, fmt);
> > @@ -100,18 +118,7 @@ void nilfs_error(struct super_block *sb, const char *function,
> > va_end(args);
> >
> > if (!(sb->s_flags & MS_RDONLY)) {
> > - struct the_nilfs *nilfs = sbi->s_nilfs;
> > -
> > - down_write(&nilfs->ns_sem);
> > - if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
> > - nilfs->ns_mount_state |= NILFS_ERROR_FS;
> > - sbp = nilfs_prepare_super(sbi);
> > - if (likely(sbp)) {
> > - sbp[0]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
> > - nilfs_commit_super(sbi, 1);
> > - }
> > - }
> > - up_write(&nilfs->ns_sem);
> > + nilfs_set_error(sbi);
> >
> > if (nilfs_test_opt(sbi, ERRORS_RO)) {
> > printk(KERN_CRIT "Remounting filesystem read-only\n");
> > @@ -179,7 +186,7 @@ static void nilfs_clear_inode(struct inode *inode)
> > nilfs_btnode_cache_clear(&ii->i_btnode_cache);
> > }
> >
> > -static int nilfs_sync_super(struct nilfs_sb_info *sbi, int dupsb)
> > +static int nilfs_sync_super(struct nilfs_sb_info *sbi, int flag)
> > {
> > struct the_nilfs *nilfs = sbi->s_nilfs;
> > int err;
> > @@ -205,12 +212,20 @@ static int nilfs_sync_super(struct nilfs_sb_info *sbi, int dupsb)
> > printk(KERN_ERR
> > "NILFS: unable to write superblock (err=%d)\n", err);
> > if (err == -EIO && nilfs->ns_sbh[1]) {
> > + /*
> > + * sbp[0] points to newer log than sbp[1],
> > + * so copy sbp[0] to sbp[1] to take over sbp[0].
> > + */
> > + memcpy(nilfs->ns_sbp[1], nilfs->ns_sbp[0],
> > + nilfs->ns_sbsize);
> > nilfs_fall_back_super_block(nilfs);
> > goto retry;
> > }
> > } else {
> > struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
> >
> > + nilfs->ns_sbwcount++;
> > +
> > /*
> > * The latest segment becomes trailable from the position
> > * written in superblock.
> > @@ -220,11 +235,14 @@ static int nilfs_sync_super(struct nilfs_sb_info *sbi, int dupsb)
> > /* update GC protection for recent segments */
> > if (nilfs->ns_sbh[1]) {
> > sbp = NULL;
> > - if (dupsb) {
> > + if (flag == NILFS_SB_COMMIT_ALL) {
> > set_buffer_dirty(nilfs->ns_sbh[1]);
> > if (!sync_dirty_buffer(nilfs->ns_sbh[1]))
> > sbp = nilfs->ns_sbp[1];
> > }
> > + if (sbp &&
> > + nilfs->ns_sbp[0]->s_last_cno < sbp->s_last_cno)
> > + sbp = nilfs->ns_sbp[0];
> > }
> > if (sbp) {
> > spin_lock(&nilfs->ns_last_segment_lock);
> > @@ -236,7 +254,8 @@ static int nilfs_sync_super(struct nilfs_sb_info *sbi, int dupsb)
> > return err;
> > }
> >
> > -struct nilfs_super_block **nilfs_prepare_super(struct nilfs_sb_info *sbi)
> > +struct nilfs_super_block **nilfs_prepare_super(struct nilfs_sb_info *sbi,
> > + int flip)
> > {
> > struct the_nilfs *nilfs = sbi->s_nilfs;
> > struct nilfs_super_block **sbp = nilfs->ns_sbp;
> > @@ -245,50 +264,62 @@ struct nilfs_super_block **nilfs_prepare_super(struct nilfs_sb_info *sbi)
> > if (sbp[0]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
> > if (sbp[1] &&
> > sbp[1]->s_magic == cpu_to_le16(NILFS_SUPER_MAGIC)) {
> > - nilfs_swap_super_block(nilfs);
> > + memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
> > } else {
> > printk(KERN_CRIT "NILFS: superblock broke on dev %s\n",
> > sbi->s_super->s_id);
> > return NULL;
> > }
> > + } else if (sbp[1] &&
> > + sbp[1]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
> > + memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
> > }
> > +
> > + if (flip && sbp[1])
> > + nilfs_swap_super_block(nilfs);
> > +
> > return sbp;
> > }
> >
> > -int nilfs_commit_super(struct nilfs_sb_info *sbi, int dupsb)
> > +void nilfs_set_log_cursor(struct nilfs_super_block *sbp,
> > + struct the_nilfs *nilfs)
> > {
> > - struct the_nilfs *nilfs = sbi->s_nilfs;
> > - struct nilfs_super_block **sbp = nilfs->ns_sbp;
> > sector_t nfreeblocks;
> > - time_t t;
> > - int err;
> >
> > /* nilfs->ns_sem must be locked by the caller. */
> > - err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
> > - if (unlikely(err)) {
> > - printk(KERN_ERR "NILFS: failed to count free blocks\n");
> > - return err;
> > - }
> > + nilfs_count_free_blocks(nilfs, &nfreeblocks);
> > + sbp->s_free_blocks_count = cpu_to_le64(nfreeblocks);
> > +
> > spin_lock(&nilfs->ns_last_segment_lock);
> > - sbp[0]->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
> > - sbp[0]->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
> > - sbp[0]->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
> > + sbp->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
> > + sbp->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
> > + sbp->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
> > spin_unlock(&nilfs->ns_last_segment_lock);
> > +}
> > +
> > +int nilfs_commit_super(struct nilfs_sb_info *sbi, int flag)
> > +{
> > + struct the_nilfs *nilfs = sbi->s_nilfs;
> > + struct nilfs_super_block **sbp = nilfs->ns_sbp;
> > + time_t t;
> >
> > + /* nilfs->ns_sem must be locked by the caller. */
> > t = get_seconds();
> > - nilfs->ns_sbwtime[0] = t;
> > - sbp[0]->s_free_blocks_count = cpu_to_le64(nfreeblocks);
> > + nilfs->ns_sbwtime = t;
> > sbp[0]->s_wtime = cpu_to_le64(t);
> > sbp[0]->s_sum = 0;
> > sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
> > (unsigned char *)sbp[0],
> > nilfs->ns_sbsize));
> > - if (dupsb && sbp[1]) {
> > - memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
> > - nilfs->ns_sbwtime[1] = t;
> > + if (flag == NILFS_SB_COMMIT_ALL && sbp[1]) {
> > + sbp[1]->s_wtime = sbp[0]->s_wtime;
> > + sbp[1]->s_sum = 0;
> > + sbp[1]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
> > + (unsigned char *)sbp[1],
> > + nilfs->ns_sbsize));
> > }
> > clear_nilfs_sb_dirty(nilfs);
> > - return nilfs_sync_super(sbi, dupsb);
> > + return nilfs_sync_super(sbi, flag);
> > }
> >
> > static void nilfs_put_super(struct super_block *sb)
> > @@ -303,10 +334,12 @@ static void nilfs_put_super(struct super_block *sb)
> >
> > if (!(sb->s_flags & MS_RDONLY)) {
> > down_write(&nilfs->ns_sem);
> > - sbp = nilfs_prepare_super(sbi);
> > + sbp = nilfs_prepare_super(sbi, 0);
> > if (likely(sbp)) {
> > + /* set state only for newer super block */
> > sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
> > - nilfs_commit_super(sbi, 1);
> > + nilfs_set_log_cursor(sbp[0], nilfs);
> > + nilfs_commit_super(sbi, NILFS_SB_COMMIT);
> > }
> > up_write(&nilfs->ns_sem);
> > }
> > @@ -328,6 +361,7 @@ static int nilfs_sync_fs(struct super_block *sb, int wait)
> > {
> > struct nilfs_sb_info *sbi = NILFS_SB(sb);
> > struct the_nilfs *nilfs = sbi->s_nilfs;
> > + struct nilfs_super_block **sbp;
> > int err = 0;
> >
> > /* This function is called when super block should be written back */
> > @@ -335,8 +369,13 @@ static int nilfs_sync_fs(struct super_block *sb, int wait)
> > err = nilfs_construct_segment(sb);
> >
> > down_write(&nilfs->ns_sem);
> > - if (nilfs_sb_dirty(nilfs) && nilfs_prepare_super(sbi))
> > - nilfs_commit_super(sbi, 1);
> > + if (nilfs_sb_dirty(nilfs)) {
> > + sbp = nilfs_prepare_super(sbi, nilfs_sb_need_swap(nilfs));
> > + if (likely(sbp)) {
> > + nilfs_set_log_cursor(sbp[0], nilfs);
> > + nilfs_commit_super(sbi, NILFS_SB_COMMIT);
> > + }
> > + }
> > up_write(&nilfs->ns_sem);
> >
> > return err;
> > @@ -635,14 +674,13 @@ static int nilfs_setup_super(struct nilfs_sb_info *sbi)
> > int mnt_count;
> >
> > /* nilfs->ns_sem must be locked by the caller. */
> > - sbp = nilfs_prepare_super(sbi);
> > + sbp = nilfs_prepare_super(sbi, 0);
> > if (!sbp)
> > return -EIO;
> >
> > max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
> > mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
> >
> > - /* nilfs->ns_sem must be locked by the caller. */
> > if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
> > printk(KERN_WARNING
> > "NILFS warning: mounting fs with errors\n");
> > @@ -659,7 +697,9 @@ static int nilfs_setup_super(struct nilfs_sb_info *sbi)
> > sbp[0]->s_state =
> > cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
> > sbp[0]->s_mtime = cpu_to_le64(get_seconds());
> > - return nilfs_commit_super(sbi, 1);
> > + /* synchronize sbp[1] with sbp[0] */
> > + memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
> > + return nilfs_commit_super(sbi, NILFS_SB_COMMIT_ALL);
> > }
> >
> > struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
> > @@ -906,14 +946,15 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
> > * the RDONLY flag and then mark the partition as valid again.
> > */
> > down_write(&nilfs->ns_sem);
> > - sbp = nilfs_prepare_super(sbi);
> > + sbp = nilfs_prepare_super(sbi, 0);
> > if (likely(sbp)) {
> > if (!(sbp[0]->s_state & le16_to_cpu(NILFS_VALID_FS)) &&
> > (nilfs->ns_mount_state & NILFS_VALID_FS))
> > sbp[0]->s_state =
> > cpu_to_le16(nilfs->ns_mount_state);
> > sbp[0]->s_mtime = cpu_to_le64(get_seconds());
> > - nilfs_commit_super(sbi, 1);
> > + nilfs_set_log_cursor(sbp[0], nilfs);
> > + nilfs_commit_super(sbi, NILFS_SB_COMMIT);
> > }
> > up_write(&nilfs->ns_sem);
> > } else {
> > diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
> > index 74b0480..7fdb780 100644
> > --- a/fs/nilfs2/the_nilfs.c
> > +++ b/fs/nilfs2/the_nilfs.c
> > @@ -326,11 +326,13 @@ int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
> >
> > down_write(&nilfs->ns_sem);
> > err = -EIO;
> > - sbp = nilfs_prepare_super(sbi);
> > + sbp = nilfs_prepare_super(sbi, 0);
> > if (likely(sbp)) {
> > nilfs->ns_mount_state |= NILFS_VALID_FS;
> > + /* set the flag only for newer super block */
> > sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
> > - err = nilfs_commit_super(sbi, 1);
> > + nilfs_set_log_cursor(sbp[0], nilfs);
> > + err = nilfs_commit_super(sbi, NILFS_SB_COMMIT);
> > }
> > up_write(&nilfs->ns_sem);
> >
> > @@ -519,8 +521,8 @@ static int nilfs_load_super_block(struct the_nilfs *nilfs,
> > nilfs_swap_super_block(nilfs);
> > }
> >
> > - nilfs->ns_sbwtime[0] = le64_to_cpu(sbp[0]->s_wtime);
> > - nilfs->ns_sbwtime[1] = valid[!swp] ? le64_to_cpu(sbp[1]->s_wtime) : 0;
> > + nilfs->ns_sbwcount = 0;
> > + nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
> > nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
> > *sbpp = sbp[0];
> > return 0;
> > diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
> > index 85df47f..0a44688 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
> > @@ -120,7 +121,8 @@ 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;
> >
> > @@ -205,20 +207,17 @@ 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_need_swap(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);
> > --
> > 1.5.6.5
> >
> --
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>
>
--
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