f2fs: change to use rwsem for cp_mutex

Use rwsem to ensure serialization of the callers and to avoid
starvation of high priority tasks, when the system is under
heavy IO workload.

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 9b0628e..e5d2ffa 100644 (file)
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -348,13 +348,13 @@ static int f2fs_write_meta_pages(struct address_space *mapping,
                goto skip_write;
 
        /* if locked failed, cp will flush dirty pages instead */
-       if (!mutex_trylock(&sbi->cp_mutex))
+       if (!down_write_trylock(&sbi->cp_global_sem))
                goto skip_write;
 
        trace_f2fs_writepages(mapping->host, wbc, META);
        diff = nr_pages_to_write(sbi, META, wbc);
        written = f2fs_sync_meta_pages(sbi, META, wbc->nr_to_write, FS_META_IO);
-       mutex_unlock(&sbi->cp_mutex);
+       up_write(&sbi->cp_global_sem);
        wbc->nr_to_write = max((long)0, wbc->nr_to_write - written - diff);
        return 0;
 
@@ -1572,7 +1572,7 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
                f2fs_warn(sbi, "Start checkpoint disabled!");
        }
        if (cpc->reason != CP_RESIZE)
-               mutex_lock(&sbi->cp_mutex);
+               down_write(&sbi->cp_global_sem);
 
        if (!is_sbi_flag_set(sbi, SBI_IS_DIRTY) &&
                ((cpc->reason & CP_FASTBOOT) || (cpc->reason & CP_SYNC) ||
@@ -1647,7 +1647,7 @@ stop:
        trace_f2fs_write_checkpoint(sbi->sb, cpc->reason, "finish checkpoint");
 out:
        if (cpc->reason != CP_RESIZE)
-               mutex_unlock(&sbi->cp_mutex);
+               up_write(&sbi->cp_global_sem);
        return err;
 }
 

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index c626fb0..273f068 100644 (file)
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1369,7 +1369,7 @@ struct f2fs_sb_info {
        int cur_cp_pack;                        /* remain current cp pack */
        spinlock_t cp_lock;                     /* for flag in ckpt */
        struct inode *meta_inode;               /* cache meta blocks */
-       struct mutex cp_mutex;                  /* checkpoint procedure lock */
+       struct rw_semaphore cp_global_sem;      /* checkpoint procedure lock */
        struct rw_semaphore cp_rwsem;           /* blocking FS operations */
        struct rw_semaphore node_write;         /* locking node writes */
        struct rw_semaphore node_change;        /* locking node change */

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 05641a1..3ef84e6 100644 (file)
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -1986,7 +1986,7 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
 
        freeze_super(sbi->sb);
        down_write(&sbi->gc_lock);
-       mutex_lock(&sbi->cp_mutex);
+       down_write(&sbi->cp_global_sem);
 
        spin_lock(&sbi->stat_lock);
        if (shrunk_blocks + valid_user_blocks(sbi) +
@@ -2031,7 +2031,7 @@ recover_out:
                spin_unlock(&sbi->stat_lock);
        }
 out_err:
-       mutex_unlock(&sbi->cp_mutex);
+       up_write(&sbi->cp_global_sem);
        up_write(&sbi->gc_lock);
        thaw_super(sbi->sb);
        clear_sbi_flag(sbi, SBI_IS_RESIZEFS);

diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index 0947d36..da75d5d 100644 (file)
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -799,7 +799,7 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only)
        INIT_LIST_HEAD(&dir_list);
 
        /* prevent checkpoint */
-       mutex_lock(&sbi->cp_mutex);
+       down_write(&sbi->cp_global_sem);
 
        /* step #1: find fsynced inode numbers */
        err = find_fsync_dnodes(sbi, &inode_list, check_only);
@@ -850,7 +850,7 @@ skip:
        if (!err)
                clear_sbi_flag(sbi, SBI_POR_DOING);
 
-       mutex_unlock(&sbi->cp_mutex);
+       up_write(&sbi->cp_global_sem);
 
        /* let's drop all the directory inodes for clean checkpoint */
        destroy_fsync_dnodes(&dir_list, err);

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 1c282c3..82baaa8 100644 (file)
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -3551,7 +3551,7 @@ try_onemore:
        sbi->valid_super_block = valid_super_block;
        init_rwsem(&sbi->gc_lock);
        mutex_init(&sbi->writepages);
-       mutex_init(&sbi->cp_mutex);
+       init_rwsem(&sbi->cp_global_sem);
        init_rwsem(&sbi->node_write);
        init_rwsem(&sbi->node_change);