f2fs: don't get FREEZE lock in f2fs_evict_inode in frozen fs

Let's purge inode cache in order to avoid the below deadlock.

[freeze test]                         shrinkder
freeze_super
 - pwercpu_down_write(SB_FREEZE_FS)
                                       - super_cache_scan
                                         - down_read(&sb->s_umount)
                                           - prune_icache_sb
                                            - dispose_list
                                             - evict
                                              - f2fs_evict_inode
thaw_super
 - down_write(&sb->s_umount);
                                              - __percpu_down_read(SB_FREEZE_FS)

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index 58bf0dc..5a5f3c5 100644 (file)
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -458,6 +458,7 @@ Description:        Show status of f2fs superblock in real time.
                0x800  SBI_QUOTA_SKIP_FLUSH  skip flushing quota in current CP
                0x1000 SBI_QUOTA_NEED_REPAIR quota file may be corrupted
                0x2000 SBI_IS_RESIZEFS       resizefs is in process
+               0x4000 SBI_IS_FREEZING       freefs is in process
                ====== ===================== =================================
 
 What:          /sys/fs/f2fs/<disk>/ckpt_thread_ioprio

diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index 9a13902..cba5eab 100644 (file)
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -338,6 +338,7 @@ static char *s_flag[] = {
        [SBI_QUOTA_SKIP_FLUSH]  = " quota_skip_flush",
        [SBI_QUOTA_NEED_REPAIR] = " quota_need_repair",
        [SBI_IS_RESIZEFS]       = " resizefs",
+       [SBI_IS_FREEZING]       = " freezefs",
 };
 
 static int stat_show(struct seq_file *s, void *v)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 68d791e..da729f5 100644 (file)
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1293,6 +1293,7 @@ enum {
        SBI_QUOTA_SKIP_FLUSH,                   /* skip flushing quota in current CP */
        SBI_QUOTA_NEED_REPAIR,                  /* quota file may be corrupted */
        SBI_IS_RESIZEFS,                        /* resizefs is in process */
+       SBI_IS_FREEZING,                        /* freezefs is in process */
 };
 
 enum {

diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index ab8e0c0..71f232d 100644 (file)
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -778,7 +778,8 @@ void f2fs_evict_inode(struct inode *inode)
        f2fs_remove_ino_entry(sbi, inode->i_ino, UPDATE_INO);
        f2fs_remove_ino_entry(sbi, inode->i_ino, FLUSH_INO);
 
-       sb_start_intwrite(inode->i_sb);
+       if (!is_sbi_flag_set(sbi, SBI_IS_FREEZING))
+               sb_start_intwrite(inode->i_sb);
        set_inode_flag(inode, FI_NO_ALLOC);
        i_size_write(inode, 0);
 retry:
@@ -809,7 +810,8 @@ retry:
                if (dquot_initialize_needed(inode))
                        set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR);
        }
-       sb_end_intwrite(inode->i_sb);
+       if (!is_sbi_flag_set(sbi, SBI_IS_FREEZING))
+               sb_end_intwrite(inode->i_sb);
 no_delete:
        dquot_drop(inode);
 

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 8e38409..4b570b5 100644 (file)
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1663,11 +1663,15 @@ static int f2fs_freeze(struct super_block *sb)
        /* ensure no checkpoint required */
        if (!llist_empty(&F2FS_SB(sb)->cprc_info.issue_list))
                return -EINVAL;
+
+       /* to avoid deadlock on f2fs_evict_inode->SB_FREEZE_FS */
+       set_sbi_flag(F2FS_SB(sb), SBI_IS_FREEZING);
        return 0;
 }
 
 static int f2fs_unfreeze(struct super_block *sb)
 {
+       clear_sbi_flag(F2FS_SB(sb), SBI_IS_FREEZING);
        return 0;
 }