f2fs: fix to access i_size w/ i_size_read()

It recommends to use i_size_{read,write}() to access and update i_size,
otherwise, we may get wrong tearing value due to high 32-bits value
and low 32-bits value of i_size field are not updated atomically in
32-bits archicture machine.

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

Author: chaseyu

include/trace/events/f2fs.h

@@ -204,7 +204,7 @@ DECLARE_EVENT_CLASS(f2fs__inode,
 		__entry->pino	= F2FS_I(inode)->i_pino;
 		__entry->mode	= inode->i_mode;
 		__entry->nlink	= inode->i_nlink;
-		__entry->size	= inode->i_size;
+		__entry->size	= i_size_read(inode);
 		__entry->blocks	= inode->i_blocks;
 		__entry->advise	= F2FS_I(inode)->i_advise;
 	),
@@ -353,7 +353,7 @@ TRACE_EVENT(f2fs_unlink_enter,
 	TP_fast_assign(
 		__entry->dev	= dir->i_sb->s_dev;
 		__entry->ino	= dir->i_ino;
-		__entry->size	= dir->i_size;
+		__entry->size	= i_size_read(dir);
 		__entry->blocks	= dir->i_blocks;
 		__assign_str(name);
 	),
@@ -433,7 +433,7 @@ DECLARE_EVENT_CLASS(f2fs__truncate_op,
 	TP_fast_assign(
 		__entry->dev	= inode->i_sb->s_dev;
 		__entry->ino	= inode->i_ino;
-		__entry->size	= inode->i_size;
+		__entry->size	= i_size_read(inode);
 		__entry->blocks	= inode->i_blocks;
 		__entry->from	= from;
 	),
@@ -1006,7 +1006,7 @@ TRACE_EVENT(f2fs_fallocate,
 		__entry->mode	= mode;
 		__entry->offset	= offset;
 		__entry->len	= len;
-		__entry->size	= inode->i_size;
+		__entry->size	= i_size_read(inode);
 		__entry->blocks = inode->i_blocks;
 		__entry->ret	= ret;
 	),