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SubjectRe: [PATCH] f2fs: prevent meta updates while checkpoint is in progress
On 03/31, Sahitya Tummala wrote:
> On Mon, Mar 30, 2020 at 08:54:19PM -0700, Jaegeuk Kim wrote:
> > On 03/26, Sahitya Tummala wrote:
> > > allocate_segment_for_resize() can cause metapage updates if
> > > it requires to change the current node/data segments for resizing.
> > > Stop these meta updates when there is a checkpoint already
> > > in progress to prevent inconsistent CP data.
> >
> > I'd prefer to use f2fs_lock_op() in bigger coverage.
>
> Do you mean to cover the entire free_segment_range() function within
> f2fs_lock_op()? Please clarify.

I didn't test tho, something like this?

---
fs/f2fs/checkpoint.c | 6 ++++--
fs/f2fs/f2fs.h | 2 +-
fs/f2fs/gc.c | 28 ++++++++++++++--------------
fs/f2fs/super.c | 1 -
include/trace/events/f2fs.h | 4 +++-
5 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 852890b72d6ac..531995192b714 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1553,7 +1553,8 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
return 0;
f2fs_warn(sbi, "Start checkpoint disabled!");
}
- mutex_lock(&sbi->cp_mutex);
+ if (cpc->reason != CP_RESIZE)
+ mutex_lock(&sbi->cp_mutex);

if (!is_sbi_flag_set(sbi, SBI_IS_DIRTY) &&
((cpc->reason & CP_FASTBOOT) || (cpc->reason & CP_SYNC) ||
@@ -1622,7 +1623,8 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
f2fs_update_time(sbi, CP_TIME);
trace_f2fs_write_checkpoint(sbi->sb, cpc->reason, "finish checkpoint");
out:
- mutex_unlock(&sbi->cp_mutex);
+ if (cpc->reason != CP_RESIZE)
+ mutex_unlock(&sbi->cp_mutex);
return err;
}

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index c84442eefc56d..7c98dca3ec1d6 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -193,6 +193,7 @@ enum {
#define CP_DISCARD 0x00000010
#define CP_TRIMMED 0x00000020
#define CP_PAUSE 0x00000040
+#define CP_RESIZE 0x00000080

#define MAX_DISCARD_BLOCKS(sbi) BLKS_PER_SEC(sbi)
#define DEF_MAX_DISCARD_REQUEST 8 /* issue 8 discards per round */
@@ -1417,7 +1418,6 @@ struct f2fs_sb_info {
unsigned int segs_per_sec; /* segments per section */
unsigned int secs_per_zone; /* sections per zone */
unsigned int total_sections; /* total section count */
- struct mutex resize_mutex; /* for resize exclusion */
unsigned int total_node_count; /* total node block count */
unsigned int total_valid_node_count; /* valid node block count */
loff_t max_file_blocks; /* max block index of file */
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 26248c8936db0..1e5a06fda09d3 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -1402,8 +1402,9 @@ void f2fs_build_gc_manager(struct f2fs_sb_info *sbi)
static int free_segment_range(struct f2fs_sb_info *sbi, unsigned int start,
unsigned int end)
{
- int type;
unsigned int segno, next_inuse;
+ struct cp_control cpc = { CP_RESIZE, 0, 0, 0 };
+ int type;
int err = 0;

/* Move out cursegs from the target range */
@@ -1417,16 +1418,14 @@ static int free_segment_range(struct f2fs_sb_info *sbi, unsigned int start,
.iroot = RADIX_TREE_INIT(gc_list.iroot, GFP_NOFS),
};

- down_write(&sbi->gc_lock);
do_garbage_collect(sbi, segno, &gc_list, FG_GC);
- up_write(&sbi->gc_lock);
put_gc_inode(&gc_list);

if (get_valid_blocks(sbi, segno, true))
return -EAGAIN;
}

- err = f2fs_sync_fs(sbi->sb, 1);
+ err = f2fs_write_checkpoint(sbi, &cpc);
if (err)
return err;

@@ -1502,6 +1501,7 @@ static void update_fs_metadata(struct f2fs_sb_info *sbi, int secs)
int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
{
__u64 old_block_count, shrunk_blocks;
+ struct cp_control cpc = { CP_RESIZE, 0, 0, 0 };
unsigned int secs;
int gc_mode, gc_type;
int err = 0;
@@ -1538,7 +1538,9 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
return -EINVAL;
}

- freeze_bdev(sbi->sb->s_bdev);
+ freeze_super(sbi->sb);
+ down_write(&sbi->gc_lock);
+ mutex_lock(&sbi->cp_mutex);

shrunk_blocks = old_block_count - block_count;
secs = div_u64(shrunk_blocks, BLKS_PER_SEC(sbi));
@@ -1551,11 +1553,12 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
sbi->user_block_count -= shrunk_blocks;
spin_unlock(&sbi->stat_lock);
if (err) {
- thaw_bdev(sbi->sb->s_bdev, sbi->sb);
+ mutex_unlock(&sbi->cp_mutex);
+ up_write(&sbi->gc_lock);
+ thaw_super(sbi->sb);
return err;
}

- mutex_lock(&sbi->resize_mutex);
set_sbi_flag(sbi, SBI_IS_RESIZEFS);

mutex_lock(&DIRTY_I(sbi)->seglist_lock);
@@ -1587,17 +1590,13 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
goto out;
}

- mutex_lock(&sbi->cp_mutex);
update_fs_metadata(sbi, -secs);
clear_sbi_flag(sbi, SBI_IS_RESIZEFS);
set_sbi_flag(sbi, SBI_IS_DIRTY);
- mutex_unlock(&sbi->cp_mutex);

- err = f2fs_sync_fs(sbi->sb, 1);
+ err = f2fs_write_checkpoint(sbi, &cpc);
if (err) {
- mutex_lock(&sbi->cp_mutex);
update_fs_metadata(sbi, secs);
- mutex_unlock(&sbi->cp_mutex);
update_sb_metadata(sbi, secs);
f2fs_commit_super(sbi, false);
}
@@ -1612,7 +1611,8 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
spin_unlock(&sbi->stat_lock);
}
clear_sbi_flag(sbi, SBI_IS_RESIZEFS);
- mutex_unlock(&sbi->resize_mutex);
- thaw_bdev(sbi->sb->s_bdev, sbi->sb);
+ mutex_unlock(&sbi->cp_mutex);
+ up_write(&sbi->gc_lock);
+ thaw_super(sbi->sb);
return err;
}
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index b83b17b54a0a6..1e7b1d21d0177 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -3412,7 +3412,6 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
init_rwsem(&sbi->gc_lock);
mutex_init(&sbi->writepages);
mutex_init(&sbi->cp_mutex);
- mutex_init(&sbi->resize_mutex);
init_rwsem(&sbi->node_write);
init_rwsem(&sbi->node_change);

diff --git a/include/trace/events/f2fs.h b/include/trace/events/f2fs.h
index d97adfc327f03..f5eb03c54e96f 100644
--- a/include/trace/events/f2fs.h
+++ b/include/trace/events/f2fs.h
@@ -50,6 +50,7 @@ TRACE_DEFINE_ENUM(CP_RECOVERY);
TRACE_DEFINE_ENUM(CP_DISCARD);
TRACE_DEFINE_ENUM(CP_TRIMMED);
TRACE_DEFINE_ENUM(CP_PAUSE);
+TRACE_DEFINE_ENUM(CP_RESIZE);

#define show_block_type(type) \
__print_symbolic(type, \
@@ -126,7 +127,8 @@ TRACE_DEFINE_ENUM(CP_PAUSE);
{ CP_RECOVERY, "Recovery" }, \
{ CP_DISCARD, "Discard" }, \
{ CP_PAUSE, "Pause" }, \
- { CP_TRIMMED, "Trimmed" })
+ { CP_TRIMMED, "Trimmed" }, \
+ { CP_RESIZE, "Resize" })

#define show_fsync_cpreason(type) \
__print_symbolic(type, \
--
2.26.0.rc2.310.g2932bb562d-goog
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