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/check-integrity.c | |
| parent | 17ca04aff7e6171df684b7b65804df8830eb8c15 (diff) | |
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/check-integrity.c')
| -rw-r--r-- | fs/btrfs/check-integrity.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c index 9cebb1fd6a3..da6e9364a5e 100644 --- a/fs/btrfs/check-integrity.c +++ b/fs/btrfs/check-integrity.c @@ -93,6 +93,7 @@ #include "print-tree.h" #include "locking.h" #include "check-integrity.h" +#include "rcu-string.h" #define BTRFSIC_BLOCK_HASHTABLE_SIZE 0x10000 #define BTRFSIC_BLOCK_LINK_HASHTABLE_SIZE 0x10000 @@ -843,13 +844,14 @@ static int btrfsic_process_superblock_dev_mirror( superblock_tmp->never_written = 0; superblock_tmp->mirror_num = 1 + superblock_mirror_num; if (state->print_mask & BTRFSIC_PRINT_MASK_SUPERBLOCK_WRITE) - printk(KERN_INFO "New initial S-block (bdev %p, %s)" - " @%llu (%s/%llu/%d)\n", - superblock_bdev, device->name, - (unsigned long long)dev_bytenr, - dev_state->name, - (unsigned long long)dev_bytenr, - superblock_mirror_num); + printk_in_rcu(KERN_INFO "New initial S-block (bdev %p, %s)" + " @%llu (%s/%llu/%d)\n", + superblock_bdev, + rcu_str_deref(device->name), + (unsigned long long)dev_bytenr, + dev_state->name, + (unsigned long long)dev_bytenr, + superblock_mirror_num); list_add(&superblock_tmp->all_blocks_node, &state->all_blocks_list); btrfsic_block_hashtable_add(superblock_tmp, |