On Tue, 24 Feb 2015 20:01:40 +0100, Andreas Rohner wrote:
> This patch adds simple tracking of block deletions and updates for
> all files except the DAT- and the SUFILE-Metadatafiles. It uses the
> fact, that for every block, NILFS2 keeps an entry in the DAT-File
> and stores the checkpoint where it was created and deleted or
> overwritten. So whenever a block is deleted or overwritten
> nilfs_dat_commit_end() is called to update the DAT-Entry. At this
> point this patch simply decrements the su_nlive_blks field of the
> corresponding segment. The value of su_nlive_blks is set at segment
> creation time.
>
> The blocks of the DAT-File cannot be counted this way, because it
> does not contain any entries about itself, so the function
> nilfs_dat_commit_end() is not called when its blocks are deleted or
> overwritten.
>
> The SUFILE cannot be counted this way, because it would lead to a
> deadlock. When nilfs_dat_commit_end() is called, the bmap->b_sem is
> held by code way up the call chain. To decrement the SUFILE entry
> the same semaphore has to be aquired. So if the DAT-Entry belongs to
> the SUFILE both semaphores are the same and a deadlock will occur.
> But it works for any other file. So by excluding the SUFILE from
> being counted by the extra parameter count_blocks a deadlock can be
> avoided.
>
> With the above changes the code does not pass the lock dependency
> checks of the kernel, because all the locks have the same class and
> the order in which the locks are taken is different. Usually it is:
>
> 1. down_write(&NILFS_MDT(sufile)->mi_sem);
> 2. down_write(&bmap->b_sem);
>
> Now it can also be reversed, which leads to failed checks:
>
> 1. down_write(&bmap->b_sem); /* lock of a file other than SUFILE */
> 2. down_write(&NILFS_MDT(sufile)->mi_sem);
>
> But this is safe as long as the first lock down_write(&bmap->b_sem)
> doesn't belong to the SUFILE.
>
> It is also possible, that two bmap->b_sem locks have to be taken at
> the same time:
>
> 1. down_write(&bmap->b_sem); /* lock of a file other than SUFILE */
> 2. down_write(&bmap->b_sem); /* lock of SUFILE */
>
> Since bmap->b_sem of normal files and the bmap->b_sem of the
> SUFILE have the same lock class, the above behavior would also lead
> to a warning.
>
> Because of this, it is necessary to introduce two new lock classes
> for the SUFILE. So the bmap->b_sem of the SUFILE gets its own lock
> class and the NILFS_MDT(sufile)->mi_sem as well.
>
> A new feature compatibility flag
> NILFS_FEATURE_COMPAT_TRACK_LIVE_BLKS was added, so that the new
> features introduced by this patch can be enabled or disabled at any
> time.
>
> Signed-off-by: Andreas Rohner <andreas.roh...@gmx.net>
> ---
> fs/nilfs2/bmap.c | 8 +++++++-
> fs/nilfs2/bmap.h | 5 +++--
> fs/nilfs2/btree.c | 4 +++-
> fs/nilfs2/dat.c | 25 ++++++++++++++++++++-----
> fs/nilfs2/dat.h | 7 +++++--
> fs/nilfs2/direct.c | 4 +++-
> fs/nilfs2/mdt.c | 5 ++++-
> fs/nilfs2/segbuf.c | 1 +
> fs/nilfs2/segbuf.h | 1 +
> fs/nilfs2/segment.c | 25 +++++++++++++++++++++----
> fs/nilfs2/the_nilfs.c | 4 ++++
> fs/nilfs2/the_nilfs.h | 16 ++++++++++++++++
> include/linux/nilfs2_fs.h | 4 +++-
> 13 files changed, 91 insertions(+), 18 deletions(-)
>
> diff --git a/fs/nilfs2/bmap.c b/fs/nilfs2/bmap.c
> index aadbd0b..ecd62ba 100644
> --- a/fs/nilfs2/bmap.c
> +++ b/fs/nilfs2/bmap.c
> @@ -467,6 +467,7 @@ __u64 nilfs_bmap_find_target_in_group(const struct
> nilfs_bmap *bmap)
>
> static struct lock_class_key nilfs_bmap_dat_lock_key;
> static struct lock_class_key nilfs_bmap_mdt_lock_key;
> +static struct lock_class_key nilfs_bmap_sufile_lock_key;
>
> /**
> * nilfs_bmap_read - read a bmap from an inode
> @@ -498,12 +499,17 @@ int nilfs_bmap_read(struct nilfs_bmap *bmap, struct
> nilfs_inode *raw_inode)
> lockdep_set_class(&bmap->b_sem, &nilfs_bmap_dat_lock_key);
> break;
> case NILFS_CPFILE_INO:
> - case NILFS_SUFILE_INO:
> bmap->b_ptr_type = NILFS_BMAP_PTR_VS;
> bmap->b_last_allocated_key = 0;
> bmap->b_last_allocated_ptr = NILFS_BMAP_INVALID_PTR;
> lockdep_set_class(&bmap->b_sem, &nilfs_bmap_mdt_lock_key);
> break;
> + case NILFS_SUFILE_INO:
> + bmap->b_ptr_type = NILFS_BMAP_PTR_VS;
> + bmap->b_last_allocated_key = 0;
> + bmap->b_last_allocated_ptr = NILFS_BMAP_INVALID_PTR;
> + lockdep_set_class(&bmap->b_sem, &nilfs_bmap_sufile_lock_key);
> + break;
> case NILFS_IFILE_INO:
> lockdep_set_class(&bmap->b_sem, &nilfs_bmap_mdt_lock_key);
> /* Fall through */
> diff --git a/fs/nilfs2/bmap.h b/fs/nilfs2/bmap.h
> index b89e680..718c814 100644
> --- a/fs/nilfs2/bmap.h
> +++ b/fs/nilfs2/bmap.h
> @@ -222,8 +222,9 @@ static inline void nilfs_bmap_commit_end_ptr(struct
> nilfs_bmap *bmap,
> struct inode *dat)
> {
> if (dat)
> - nilfs_dat_commit_end(dat, &req->bpr_req,
> - bmap->b_ptr_type == NILFS_BMAP_PTR_VS);
> + nilfs_dat_commit_end(dat, &req->bpr_req, NULL,
> + bmap->b_ptr_type == NILFS_BMAP_PTR_VS,
> + bmap->b_inode->i_ino != NILFS_SUFILE_INO);
> }
>
> static inline void nilfs_bmap_abort_end_ptr(struct nilfs_bmap *bmap,
> diff --git a/fs/nilfs2/btree.c b/fs/nilfs2/btree.c
> index b2e3ff3..2af0519 100644
> --- a/fs/nilfs2/btree.c
> +++ b/fs/nilfs2/btree.c
> @@ -1851,7 +1851,9 @@ static void nilfs_btree_commit_update_v(struct
> nilfs_bmap *btree,
>
> nilfs_dat_commit_update(dat, &path[level].bp_oldreq.bpr_req,
> &path[level].bp_newreq.bpr_req,
> - btree->b_ptr_type == NILFS_BMAP_PTR_VS);
> + NULL,
> + btree->b_ptr_type == NILFS_BMAP_PTR_VS,
> + btree->b_inode->i_ino != NILFS_SUFILE_INO);
>
> if (buffer_nilfs_node(path[level].bp_bh)) {
> nilfs_btnode_commit_change_key(
> diff --git a/fs/nilfs2/dat.c b/fs/nilfs2/dat.c
> index 0d5fada..d2c8f7e 100644
> --- a/fs/nilfs2/dat.c
> +++ b/fs/nilfs2/dat.c
> @@ -28,6 +28,7 @@
> #include "mdt.h"
> #include "alloc.h"
> #include "dat.h"
> +#include "sufile.h"
>
>
> #define NILFS_CNO_MIN ((__u64)1)
> @@ -185,12 +186,14 @@ int nilfs_dat_prepare_end(struct inode *dat, struct
> nilfs_palloc_req *req)
> }
>
> void nilfs_dat_commit_end(struct inode *dat, struct nilfs_palloc_req *req,
> - int dead)
> + struct nilfs_sufile_mod_cache *mc,
> + int dead, int count_blocks)
> {
> struct nilfs_dat_entry *entry;
> - __u64 start, end;
> + __u64 start, end, segnum;
> sector_t blocknr;
> void *kaddr;
> + struct the_nilfs *nilfs;
>
> kaddr = kmap_atomic(req->pr_entry_bh->b_page);
> entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
> @@ -206,8 +209,18 @@ void nilfs_dat_commit_end(struct inode *dat, struct
> nilfs_palloc_req *req,
>
> if (blocknr == 0)
> nilfs_dat_commit_free(dat, req);
> - else
> + else {
> nilfs_dat_commit_entry(dat, req);
> +
> + nilfs = dat->i_sb->s_fs_info;
> +
> + if (count_blocks && nilfs_feature_track_live_blks(nilfs)) {
> + segnum = nilfs_get_segnum_of_block(nilfs, blocknr);
> +
> + nilfs_sufile_mod_nlive_blks(nilfs->ns_sufile, mc,
> + segnum, -1);
> + }
> + }
> }
>
> void nilfs_dat_abort_end(struct inode *dat, struct nilfs_palloc_req *req)
> @@ -246,9 +259,11 @@ int nilfs_dat_prepare_update(struct inode *dat,
>
> void nilfs_dat_commit_update(struct inode *dat,
> struct nilfs_palloc_req *oldreq,
> - struct nilfs_palloc_req *newreq, int dead)
> + struct nilfs_palloc_req *newreq,
> + struct nilfs_sufile_mod_cache *mc,
> + int dead, int count_blocks)
> {
> - nilfs_dat_commit_end(dat, oldreq, dead);
> + nilfs_dat_commit_end(dat, oldreq, mc, dead, count_blocks);
> nilfs_dat_commit_alloc(dat, newreq);
> }
>
> diff --git a/fs/nilfs2/dat.h b/fs/nilfs2/dat.h
> index cbd8e97..d196f09 100644
> --- a/fs/nilfs2/dat.h
> +++ b/fs/nilfs2/dat.h
> @@ -29,6 +29,7 @@
>
>
> struct nilfs_palloc_req;
> +struct nilfs_sufile_mod_cache;
>
> int nilfs_dat_translate(struct inode *, __u64, sector_t *);
>
> @@ -39,12 +40,14 @@ int nilfs_dat_prepare_start(struct inode *, struct
> nilfs_palloc_req *);
> void nilfs_dat_commit_start(struct inode *, struct nilfs_palloc_req *,
> sector_t);
> int nilfs_dat_prepare_end(struct inode *, struct nilfs_palloc_req *);
> -void nilfs_dat_commit_end(struct inode *, struct nilfs_palloc_req *, int);
> +void nilfs_dat_commit_end(struct inode *, struct nilfs_palloc_req *,
> + struct nilfs_sufile_mod_cache *, int, int);
> void nilfs_dat_abort_end(struct inode *, struct nilfs_palloc_req *);
> int nilfs_dat_prepare_update(struct inode *, struct nilfs_palloc_req *,
> struct nilfs_palloc_req *);
> void nilfs_dat_commit_update(struct inode *, struct nilfs_palloc_req *,
> - struct nilfs_palloc_req *, int);
> + struct nilfs_palloc_req *,
> + struct nilfs_sufile_mod_cache *, int, int);
> void nilfs_dat_abort_update(struct inode *, struct nilfs_palloc_req *,
> struct nilfs_palloc_req *);
>
> diff --git a/fs/nilfs2/direct.c b/fs/nilfs2/direct.c
> index 82f4865..e022cfb 100644
> --- a/fs/nilfs2/direct.c
> +++ b/fs/nilfs2/direct.c
> @@ -272,7 +272,9 @@ static int nilfs_direct_propagate(struct nilfs_bmap *bmap,
> if (ret < 0)
> return ret;
> nilfs_dat_commit_update(dat, &oldreq, &newreq,
> - bmap->b_ptr_type == NILFS_BMAP_PTR_VS);
> + NULL,
> + bmap->b_ptr_type == NILFS_BMAP_PTR_VS,
> + bmap->b_inode->i_ino != NILFS_SUFILE_INO);
> set_buffer_nilfs_volatile(bh);
> nilfs_direct_set_ptr(bmap, key, newreq.pr_entry_nr);
> } else
> diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c
> index 892cf5f..2a81f82 100644
> --- a/fs/nilfs2/mdt.c
> +++ b/fs/nilfs2/mdt.c
> @@ -414,7 +414,7 @@ static const struct address_space_operations def_mdt_aops
> = {
>
> static const struct inode_operations def_mdt_iops;
> static const struct file_operations def_mdt_fops;
> -
> +static struct lock_class_key nilfs_mdt_mi_sufile_lock_key;
>
> int nilfs_mdt_init(struct inode *inode, gfp_t gfp_mask, size_t objsz)
> {
> @@ -427,6 +427,9 @@ int nilfs_mdt_init(struct inode *inode, gfp_t gfp_mask,
> size_t objsz)
> init_rwsem(&mi->mi_sem);
> inode->i_private = mi;
>
> + if (inode->i_ino == NILFS_SUFILE_INO)
> + lockdep_set_class(&mi->mi_sem, &nilfs_mdt_mi_sufile_lock_key);
> +
> inode->i_mode = S_IFREG;
> mapping_set_gfp_mask(inode->i_mapping, gfp_mask);
>
> diff --git a/fs/nilfs2/segbuf.c b/fs/nilfs2/segbuf.c
> index dc3a9efd..7a6e9cd 100644
> --- a/fs/nilfs2/segbuf.c
> +++ b/fs/nilfs2/segbuf.c
> @@ -57,6 +57,7 @@ struct nilfs_segment_buffer *nilfs_segbuf_new(struct
> super_block *sb)
> INIT_LIST_HEAD(&segbuf->sb_segsum_buffers);
> INIT_LIST_HEAD(&segbuf->sb_payload_buffers);
> segbuf->sb_super_root = NULL;
> + segbuf->sb_nlive_blks_added = 0;
>
> init_completion(&segbuf->sb_bio_event);
> atomic_set(&segbuf->sb_err, 0);
> diff --git a/fs/nilfs2/segbuf.h b/fs/nilfs2/segbuf.h
> index b04f08c..d04da26 100644
> --- a/fs/nilfs2/segbuf.h
> +++ b/fs/nilfs2/segbuf.h
> @@ -83,6 +83,7 @@ struct nilfs_segment_buffer {
> sector_t sb_fseg_start, sb_fseg_end;
> sector_t sb_pseg_start;
> unsigned sb_rest_blocks;
> + __u32 sb_nlive_blks_added;
>
> /* Buffers */
> struct list_head sb_segsum_buffers;
> diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
> index 469086b..6059f53 100644
> --- a/fs/nilfs2/segment.c
> +++ b/fs/nilfs2/segment.c
> @@ -1367,9 +1367,10 @@ static void nilfs_free_incomplete_logs(struct
> list_head *logs,
> }
>
> static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
> - struct inode *sufile)
> + struct the_nilfs *nilfs)
> {
> struct nilfs_segment_buffer *segbuf;
> + struct inode *sufile = nilfs->ns_sufile;
> unsigned long live_blocks;
> int ret;
>
> @@ -1380,12 +1381,22 @@ static void nilfs_segctor_update_segusage(struct
> nilfs_sc_info *sci,
> live_blocks,
> sci->sc_seg_ctime);
> WARN_ON(ret); /* always succeed because the segusage is dirty */
> +
> + /* should always be positive */
> + segbuf->sb_nlive_blks_added = segbuf->sb_sum.nfileblk;
> +
> + if (nilfs_feature_track_live_blks(nilfs))
> + nilfs_sufile_mod_nlive_blks(sufile, NULL,
> + segbuf->sb_segnum,
> + segbuf->sb_nlive_blks_added);
> }
> }
>
> -static void nilfs_cancel_segusage(struct list_head *logs, struct inode
> *sufile)
> +static void nilfs_cancel_segusage(struct list_head *logs,
> + struct the_nilfs *nilfs)
> {
> struct nilfs_segment_buffer *segbuf;
> + struct inode *sufile = nilfs->ns_sufile;
> int ret;
>
> segbuf = NILFS_FIRST_SEGBUF(logs);
> @@ -1394,6 +1405,12 @@ static void nilfs_cancel_segusage(struct list_head
> *logs, struct inode *sufile)
> segbuf->sb_fseg_start, 0);
> WARN_ON(ret); /* always succeed because the segusage is dirty */
>
> + if (nilfs_feature_track_live_blks(nilfs))
> + nilfs_sufile_mod_nlive_blks(sufile, NULL, segbuf->sb_segnum,
> + -((__s64)segbuf->sb_nlive_blks_added));
> +
> + segbuf->sb_nlive_blks_added = 0;
> +
> list_for_each_entry_continue(segbuf, logs, sb_list) {
> ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
> 0, 0);
> @@ -1729,7 +1746,7 @@ static void nilfs_segctor_abort_construction(struct
> nilfs_sc_info *sci,
> nilfs_abort_logs(&logs, ret ? : err);
>
> list_splice_tail_init(&sci->sc_segbufs, &logs);
> - nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
> + nilfs_cancel_segusage(&logs, nilfs);
> nilfs_free_incomplete_logs(&logs, nilfs);
>
> if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
> @@ -1995,7 +2012,7 @@ static int nilfs_segctor_do_construct(struct
> nilfs_sc_info *sci, int mode)
>
> nilfs_segctor_fill_in_super_root(sci, nilfs);
> }
> - nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
> + nilfs_segctor_update_segusage(sci, nilfs);
>
> /* Write partial segments */
> nilfs_segctor_prepare_write(sci);
Please separate changes below.
> diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
> index 69bd801..606fdfc 100644
> --- a/fs/nilfs2/the_nilfs.c
> +++ b/fs/nilfs2/the_nilfs.c
> @@ -630,6 +630,10 @@ int init_nilfs(struct the_nilfs *nilfs, struct
> super_block *sb, char *data)
> get_random_bytes(&nilfs->ns_next_generation,
> sizeof(nilfs->ns_next_generation));
>
> + nilfs->ns_feature_compat = le64_to_cpu(sbp->s_feature_compat);
> + nilfs->ns_feature_compat_ro = le64_to_cpu(sbp->s_feature_compat_ro);
> + nilfs->ns_feature_incompat = le64_to_cpu(sbp->s_feature_incompat);
> +
> err = nilfs_store_disk_layout(nilfs, sbp);
> if (err)
> goto failed_sbh;
> diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
> index 23778d3..87cab10 100644
> --- a/fs/nilfs2/the_nilfs.h
> +++ b/fs/nilfs2/the_nilfs.h
> @@ -101,6 +101,9 @@ enum {
> * @ns_dev_kobj: /sys/fs/<nilfs>/<device>
> * @ns_dev_kobj_unregister: completion state
> * @ns_dev_subgroups: <device> subgroups pointer
> + * @ns_feature_compat: Compatible feature set
> + * @ns_feature_compat_ro: Read-only compatible feature set
> + * @ns_feature_incompat: Incompatible feature set
> */
> struct the_nilfs {
> unsigned long ns_flags;
> @@ -201,6 +204,11 @@ struct the_nilfs {
> struct kobject ns_dev_kobj;
> struct completion ns_dev_kobj_unregister;
> struct nilfs_sysfs_dev_subgroups *ns_dev_subgroups;
> +
> + /* Features */
> + __u64 ns_feature_compat;
> + __u64 ns_feature_compat_ro;
> + __u64 ns_feature_incompat;
> };
>
> #define THE_NILFS_FNS(bit, name) \
> @@ -393,4 +401,12 @@ static inline int nilfs_flush_device(struct the_nilfs
> *nilfs)
> return err;
> }
>
> +static inline int nilfs_feature_track_live_blks(struct the_nilfs *nilfs)
> +{
> + return (nilfs->ns_feature_compat &
> + NILFS_FEATURE_COMPAT_TRACK_LIVE_BLKS) &&
> + (nilfs->ns_feature_compat &
> + NILFS_FEATURE_COMPAT_SUFILE_EXTENSION);
> +}
> +
This should be written as below:
static inline int nilfs_feature_track_live_blks(struct the_nilfs *nilfs)
{
const __u64 required_bits = NILFS_FEATURE_COMPAT_TRACK_LIVE_BLKS |
NILFS_FEATURE_COMPAT_SUFILE_EXTENSION;
return ((nilfs->ns_feature_compat & required_bits) == required_bits);
}
Or you can drop the track flag at mount time if
NILFS_FEATURE_COMPAT_SUFILE_EXTENSION flag is not set or
nilfs_sufile_ext_supported(sufile) is false.
Regards,
Ryusuke Konishi
> #endif /* _THE_NILFS_H */
> diff --git a/include/linux/nilfs2_fs.h b/include/linux/nilfs2_fs.h
> index 5d83c55..6ccb2ad 100644
> --- a/include/linux/nilfs2_fs.h
> +++ b/include/linux/nilfs2_fs.h
> @@ -221,10 +221,12 @@ struct nilfs_super_block {
> * doesn't know about, it should refuse to mount the filesystem.
> */
> #define NILFS_FEATURE_COMPAT_SUFILE_EXTENSION (1ULL << 0)
> +#define NILFS_FEATURE_COMPAT_TRACK_LIVE_BLKS (1ULL << 1)
>
> #define NILFS_FEATURE_COMPAT_RO_BLOCK_COUNT (1ULL << 0)
>
> -#define NILFS_FEATURE_COMPAT_SUPP NILFS_FEATURE_COMPAT_SUFILE_EXTENSION
> +#define NILFS_FEATURE_COMPAT_SUPP (NILFS_FEATURE_COMPAT_SUFILE_EXTENSION \
> + | NILFS_FEATURE_COMPAT_TRACK_LIVE_BLKS)
> #define NILFS_FEATURE_COMPAT_RO_SUPP NILFS_FEATURE_COMPAT_RO_BLOCK_COUNT
> #define NILFS_FEATURE_INCOMPAT_SUPP 0ULL
>
> --
> 2.3.0
>
> --
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