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/scrub.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/scrub.c')
| -rw-r--r-- | fs/btrfs/scrub.c | 30 |
1 files changed, 18 insertions, 12 deletions
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index a38cfa4f251e..b223620cd5a6 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -26,6 +26,7 @@ #include "backref.h" #include "extent_io.h" #include "check-integrity.h" +#include "rcu-string.h" /* * This is only the first step towards a full-features scrub. It reads all @@ -320,10 +321,10 @@ static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root, void *ctx) * hold all of the paths here */ for (i = 0; i < ipath->fspath->elem_cnt; ++i) - printk(KERN_WARNING "btrfs: %s at logical %llu on dev " + printk_in_rcu(KERN_WARNING "btrfs: %s at logical %llu on dev " "%s, sector %llu, root %llu, inode %llu, offset %llu, " "length %llu, links %u (path: %s)\n", swarn->errstr, - swarn->logical, swarn->dev->name, + swarn->logical, rcu_str_deref(swarn->dev->name), (unsigned long long)swarn->sector, root, inum, offset, min(isize - offset, (u64)PAGE_SIZE), nlink, (char *)(unsigned long)ipath->fspath->val[i]); @@ -332,10 +333,10 @@ static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root, void *ctx) return 0; err: - printk(KERN_WARNING "btrfs: %s at logical %llu on dev " + printk_in_rcu(KERN_WARNING "btrfs: %s at logical %llu on dev " "%s, sector %llu, root %llu, inode %llu, offset %llu: path " "resolving failed with ret=%d\n", swarn->errstr, - swarn->logical, swarn->dev->name, + swarn->logical, rcu_str_deref(swarn->dev->name), (unsigned long long)swarn->sector, root, inum, offset, ret); free_ipath(ipath); @@ -390,10 +391,11 @@ static void scrub_print_warning(const char *errstr, struct scrub_block *sblock) do { ret = tree_backref_for_extent(&ptr, eb, ei, item_size, &ref_root, &ref_level); - printk(KERN_WARNING + printk_in_rcu(KERN_WARNING "btrfs: %s at logical %llu on dev %s, " "sector %llu: metadata %s (level %d) in tree " - "%llu\n", errstr, swarn.logical, dev->name, + "%llu\n", errstr, swarn.logical, + rcu_str_deref(dev->name), (unsigned long long)swarn.sector, ref_level ? "node" : "leaf", ret < 0 ? -1 : ref_level, @@ -580,9 +582,11 @@ out: spin_lock(&sdev->stat_lock); ++sdev->stat.uncorrectable_errors; spin_unlock(&sdev->stat_lock); - printk_ratelimited(KERN_ERR + + printk_ratelimited_in_rcu(KERN_ERR "btrfs: unable to fixup (nodatasum) error at logical %llu on dev %s\n", - (unsigned long long)fixup->logical, sdev->dev->name); + (unsigned long long)fixup->logical, + rcu_str_deref(sdev->dev->name)); } btrfs_free_path(path); @@ -936,18 +940,20 @@ corrected_error: spin_lock(&sdev->stat_lock); sdev->stat.corrected_errors++; spin_unlock(&sdev->stat_lock); - printk_ratelimited(KERN_ERR + printk_ratelimited_in_rcu(KERN_ERR "btrfs: fixed up error at logical %llu on dev %s\n", - (unsigned long long)logical, sdev->dev->name); + (unsigned long long)logical, + rcu_str_deref(sdev->dev->name)); } } else { did_not_correct_error: spin_lock(&sdev->stat_lock); sdev->stat.uncorrectable_errors++; spin_unlock(&sdev->stat_lock); - printk_ratelimited(KERN_ERR + printk_ratelimited_in_rcu(KERN_ERR "btrfs: unable to fixup (regular) error at logical %llu on dev %s\n", - (unsigned long long)logical, sdev->dev->name); + (unsigned long long)logical, + rcu_str_deref(sdev->dev->name)); } out: |