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ext4: move ext4_update_i_disksize() into mpage_map_and_submit_extent()

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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: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org
This commit is contained in:
Theodore Ts'o 2014-04-11 10:35:17 -04:00
parent c57ab39b96
commit 622cad1325
2 changed files with 12 additions and 19 deletions
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17
fs/ext4/ext4.h
View File

@ -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;

14
fs/ext4/inode.c
View File

@ -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",