f2fs: refactor resize_fs to avoid meta updates in progress

Sahitya raised an issue:
- prevent meta updates while checkpoint is in progress

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.

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/f2fs.h b/fs/f2fs/f2fs.h
index 1d96f73..3386220 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -194,6 +194,7 @@ 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 */
@@ -1471,7 +1472,6 @@ 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 */