diff options
| author | Josef Bacik <josef@redhat.com> | 2012-06-04 14:03:51 -0400 |
|---|---|---|
| committer | Chris Mason <chris.mason@oracle.com> | 2012-06-14 21:29:16 -0400 |
| commit | 606686eeac4550d2212bf3d621a810407ef5e9bf (patch) | |
| tree | 50adade3a750137b68304dc280d7a75436417b12 /fs/btrfs/disk-io.c | |
| parent | 17ca04aff7e6171df684b7b65804df8830eb8c15 (diff) | |
| download | lwn-606686eeac4550d2212bf3d621a810407ef5e9bf.tar.gz lwn-606686eeac4550d2212bf3d621a810407ef5e9bf.zip | |
Btrfs: use rcu to protect device->name
Al pointed out that we can just toss out the old name on a device and add a
new one arbitrarily, so anybody who uses device->name in printk could
possibly use free'd memory. Instead of adding locking around all of this he
suggested doing it with RCU, so I've introduced a struct rcu_string that
does just that and have gone through and protected all accesses to
device->name that aren't under the uuid_mutex with rcu_read_lock(). This
protects us and I will use it for dealing with removing the device that we
used to mount the file system in a later patch. Thanks,
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <josef@redhat.com>
Diffstat (limited to 'fs/btrfs/disk-io.c')
| -rw-r--r-- | fs/btrfs/disk-io.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 5a3bf323e2bd..1c9664b16cd1 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -44,6 +44,7 @@ #include "free-space-cache.h" #include "inode-map.h" #include "check-integrity.h" +#include "rcu-string.h" static struct extent_io_ops btree_extent_io_ops; static void end_workqueue_fn(struct btrfs_work *work); @@ -2575,8 +2576,9 @@ static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate) struct btrfs_device *device = (struct btrfs_device *) bh->b_private; - printk_ratelimited(KERN_WARNING "lost page write due to " - "I/O error on %s\n", device->name); + printk_ratelimited_in_rcu(KERN_WARNING "lost page write due to " + "I/O error on %s\n", + rcu_str_deref(device->name)); /* note, we dont' set_buffer_write_io_error because we have * our own ways of dealing with the IO errors */ @@ -2749,8 +2751,8 @@ static int write_dev_flush(struct btrfs_device *device, int wait) wait_for_completion(&device->flush_wait); if (bio_flagged(bio, BIO_EOPNOTSUPP)) { - printk("btrfs: disabling barriers on dev %s\n", - device->name); + printk_in_rcu("btrfs: disabling barriers on dev %s\n", + rcu_str_deref(device->name)); device->nobarriers = 1; } if (!bio_flagged(bio, BIO_UPTODATE)) { |