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Commit 622cad13 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: move ext4_update_i_disksize() into mpage_map_and_submit_extent() 



The function ext4_update_i_disksize() is used in only one place, in
the function mpage_map_and_submit_extent().  Move its code to simplify
the code paths, and also move the call to ext4_mark_inode_dirty() into
the i_data_sem's critical region, to be consistent with all of the
other places where we update i_disksize.  That way, we also keep the
raw_inode's i_disksize protected, to avoid the following race:

      CPU #1                                 CPU #2

   down_write(&i_data_sem)
   Modify i_disk_size
   up_write(&i_data_sem)
                                        down_write(&i_data_sem)
                                        Modify i_disk_size
                                        Copy i_disk_size to on-disk inode
                                        up_write(&i_data_sem)
   Copy i_disk_size to on-disk inode

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org
parent c57ab39b

fs/ext4/ext4.h

+0 −17
Original line number Diff line number Diff line
@@ -2466,23 +2466,6 @@ static inline void ext4_update_i_disksize(struct inode *inode, loff_t newsize) 
	up_write(&EXT4_I(inode)->i_data_sem);

}



/*

 * Update i_disksize after writeback has been started. Races with truncate

 * are avoided by checking i_size under i_data_sem.

 */

static inline void ext4_wb_update_i_disksize(struct inode *inode, loff_t newsize)

{

	loff_t i_size;



	down_write(&EXT4_I(inode)->i_data_sem);

	i_size = i_size_read(inode);

	if (newsize > i_size)

		newsize = i_size;

	if (newsize > EXT4_I(inode)->i_disksize)

		EXT4_I(inode)->i_disksize = newsize;

	up_write(&EXT4_I(inode)->i_data_sem);

}



struct ext4_group_info {

	unsigned long   bb_state;

	struct rb_root  bb_free_root;

fs/ext4/inode.c

+13 −3
Original line number Diff line number Diff line
@@ -2247,13 +2247,23 @@ static int mpage_map_and_submit_extent(handle_t *handle, 
			return err;

	} while (map->m_len);



	/* Update on-disk size after IO is submitted */

	/*

	 * Update on-disk size after IO is submitted.  Races with

	 * truncate are avoided by checking i_size under i_data_sem.

	 */

	disksize = ((loff_t)mpd->first_page) << PAGE_CACHE_SHIFT;

	if (disksize > EXT4_I(inode)->i_disksize) {

		int err2;

		loff_t i_size;



		ext4_wb_update_i_disksize(inode, disksize);

		down_write(&EXT4_I(inode)->i_data_sem);

		i_size = i_size_read(inode);

		if (disksize > i_size)

			disksize = i_size;

		if (disksize > EXT4_I(inode)->i_disksize)

			EXT4_I(inode)->i_disksize = disksize;

		err2 = ext4_mark_inode_dirty(handle, inode);

		up_write(&EXT4_I(inode)->i_data_sem);

		if (err2)

			ext4_error(inode->i_sb,

				   "Failed to mark inode %lu dirty",