1 files changed, 58 insertions, 34 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 7782020996fe..8a3d2594b807 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -35,6 +35,7 @@
 #include "volumes.h"
 #include "async-thread.h"
 #include "check-integrity.h"
+#include "rcu-string.h"
 
 static int init_first_rw_device(struct btrfs_trans_handle *trans,
                                 struct btrfs_root *root,
@@ -64,7 +65,7 @@ static void free_fs_devices(struct btrfs_fs_devices *fs_devices)
                 device = list_entry(fs_devices->devices.next,
                                     struct btrfs_device, dev_list);
                 list_del(&device->dev_list);
-                kfree(device->name);
+                rcu_string_free(device->name);
                 kfree(device);
         }
         kfree(fs_devices);
@@ -334,8 +335,8 @@ static noinline int device_list_add(const char *path,
 {
         struct btrfs_device *device;
         struct btrfs_fs_devices *fs_devices;
+        struct rcu_string *name;
         u64 found_transid = btrfs_super_generation(disk_super);
-        char *name;
 
         fs_devices = find_fsid(disk_super->fsid);
         if (!fs_devices) {
@@ -369,11 +370,13 @@ static noinline int device_list_add(const char *path,
                 memcpy(device->uuid, disk_super->dev_item.uuid,
                        BTRFS_UUID_SIZE);
                 spin_lock_init(&device->io_lock);
-                device->name = kstrdup(path, GFP_NOFS);
-                if (!device->name) {
+
+                name = rcu_string_strdup(path, GFP_NOFS);
+                if (!name) {
                         kfree(device);
                         return -ENOMEM;
                 }
+                rcu_assign_pointer(device->name, name);
                 INIT_LIST_HEAD(&device->dev_alloc_list);
 
                 /* init readahead state */
@@ -390,12 +393,12 @@ static noinline int device_list_add(const char *path,
 
                 device->fs_devices = fs_devices;
                 fs_devices->num_devices++;
-        } else if (!device->name || strcmp(device->name, path)) {
-                name = kstrdup(path, GFP_NOFS);
+        } else if (!device->name || strcmp(device->name->str, path)) {
+                name = rcu_string_strdup(path, GFP_NOFS);
                 if (!name)
                         return -ENOMEM;
-                kfree(device->name);
-                device->name = name;
+                rcu_string_free(device->name);
+                rcu_assign_pointer(device->name, name);
                 if (device->missing) {
                         fs_devices->missing_devices--;
                         device->missing = 0;
@@ -430,15 +433,22 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
 
         /* We have held the volume lock, it is safe to get the devices. */
         list_for_each_entry(orig_dev, &orig->devices, dev_list) {
+                struct rcu_string *name;
+
                 device = kzalloc(sizeof(*device), GFP_NOFS);
                 if (!device)
                         goto error;
 
-                device->name = kstrdup(orig_dev->name, GFP_NOFS);
-                if (!device->name) {
+                /*
+                 * This is ok to do without rcu read locked because we hold the
+                 * uuid mutex so nothing we touch in here is going to disappear.
+                 */
+                name = rcu_string_strdup(orig_dev->name->str, GFP_NOFS);
+                if (!name) {
                         kfree(device);
                         goto error;
                 }
+                rcu_assign_pointer(device->name, name);
 
                 device->devid = orig_dev->devid;
                 device->work.func = pending_bios_fn;
@@ -491,7 +501,7 @@ again:
                 }
                 list_del_init(&device->dev_list);
                 fs_devices->num_devices--;
-                kfree(device->name);
+                rcu_string_free(device->name);
                 kfree(device);
         }
 
@@ -516,7 +526,7 @@ static void __free_device(struct work_struct *work)
         if (device->bdev)
                 blkdev_put(device->bdev, device->mode);
 
-        kfree(device->name);
+        rcu_string_free(device->name);
         kfree(device);
 }
 
@@ -540,6 +550,7 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
         mutex_lock(&fs_devices->device_list_mutex);
         list_for_each_entry(device, &fs_devices->devices, dev_list) {
                 struct btrfs_device *new_device;
+                struct rcu_string *name;
 
                 if (device->bdev)
                         fs_devices->open_devices--;
@@ -555,8 +566,11 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
                 new_device = kmalloc(sizeof(*new_device), GFP_NOFS);
                 BUG_ON(!new_device); /* -ENOMEM */
                 memcpy(new_device, device, sizeof(*new_device));
-                new_device->name = kstrdup(device->name, GFP_NOFS);
-                BUG_ON(device->name && !new_device->name); /* -ENOMEM */
+
+                /* Safe because we are under uuid_mutex */
+                name = rcu_string_strdup(device->name->str, GFP_NOFS);
+                BUG_ON(device->name && !name); /* -ENOMEM */
+                rcu_assign_pointer(new_device->name, name);
                 new_device->bdev = NULL;
                 new_device->writeable = 0;
                 new_device->in_fs_metadata = 0;
@@ -621,9 +635,9 @@ static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
                 if (!device->name)
                         continue;
 
-                bdev = blkdev_get_by_path(device->name, flags, holder);
+                bdev = blkdev_get_by_path(device->name->str, flags, holder);
                 if (IS_ERR(bdev)) {
-                        printk(KERN_INFO "open %s failed\n", device->name);
+                        printk(KERN_INFO "open %s failed\n", device->name->str);
                         goto error;
                 }
                 filemap_write_and_wait(bdev->bd_inode->i_mapping);
@@ -1632,6 +1646,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         struct block_device *bdev;
         struct list_head *devices;
         struct super_block *sb = root->fs_info->sb;
+        struct rcu_string *name;
         u64 total_bytes;
         int seeding_dev = 0;
         int ret = 0;
@@ -1671,23 +1686,24 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
                 goto error;
         }
 
-        device->name = kstrdup(device_path, GFP_NOFS);
-        if (!device->name) {
+        name = rcu_string_strdup(device_path, GFP_NOFS);
+        if (!name) {
                 kfree(device);
                 ret = -ENOMEM;
                 goto error;
         }
+        rcu_assign_pointer(device->name, name);
 
         ret = find_next_devid(root, &device->devid);
         if (ret) {
-                kfree(device->name);
+                rcu_string_free(device->name);
                 kfree(device);
                 goto error;
         }
 
         trans = btrfs_start_transaction(root, 0);
         if (IS_ERR(trans)) {
-                kfree(device->name);
+                rcu_string_free(device->name);
                 kfree(device);
                 ret = PTR_ERR(trans);
                 goto error;
@@ -1796,7 +1812,7 @@ error_trans:
         unlock_chunks(root);
         btrfs_abort_transaction(trans, root, ret);
         btrfs_end_transaction(trans, root);
-        kfree(device->name);
+        rcu_string_free(device->name);
         kfree(device);
 error:
         blkdev_put(bdev, FMODE_EXCL);
@@ -4204,10 +4220,17 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
                 bio->bi_sector = bbio->stripes[dev_nr].physical >> 9;
                 dev = bbio->stripes[dev_nr].dev;
                 if (dev && dev->bdev && (rw != WRITE || dev->writeable)) {
+#ifdef DEBUG
+                        struct rcu_string *name;
+
+                        rcu_read_lock();
+                        name = rcu_dereference(dev->name);
                         pr_debug("btrfs_map_bio: rw %d, secor=%llu, dev=%lu "
                                  "(%s id %llu), size=%u\n", rw,
                                  (u64)bio->bi_sector, (u_long)dev->bdev->bd_dev,
-                                 dev->name, dev->devid, bio->bi_size);
+                                 name->str, dev->devid, bio->bi_size);
+                        rcu_read_unlock();
+#endif
                         bio->bi_bdev = dev->bdev;
                         if (async_submit)
                                 schedule_bio(root, dev, rw, bio);
@@ -4694,8 +4717,9 @@ int btrfs_init_dev_stats(struct btrfs_fs_info *fs_info)
                 key.offset = device->devid;
                 ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
                 if (ret) {
-                        printk(KERN_WARNING "btrfs: no dev_stats entry found for device %s (devid %llu) (OK on first mount after mkfs)\n",
-                               device->name, (unsigned long long)device->devid);
+                        printk_in_rcu(KERN_WARNING "btrfs: no dev_stats entry found for device %s (devid %llu) (OK on first mount after mkfs)\n",
+                                      rcu_str_deref(device->name),
+                                      (unsigned long long)device->devid);
                         __btrfs_reset_dev_stats(device);
                         device->dev_stats_valid = 1;
                         btrfs_release_path(path);
@@ -4747,8 +4771,8 @@ static int update_dev_stat_item(struct btrfs_trans_handle *trans,
         BUG_ON(!path);
         ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
         if (ret < 0) {
-                printk(KERN_WARNING "btrfs: error %d while searching for dev_stats item for device %s!\n",
-                       ret, device->name);
+                printk_in_rcu(KERN_WARNING "btrfs: error %d while searching for dev_stats item for device %s!\n",
+                              ret, rcu_str_deref(device->name));
                 goto out;
         }
 
@@ -4757,8 +4781,8 @@ static int update_dev_stat_item(struct btrfs_trans_handle *trans,
                 /* need to delete old one and insert a new one */
                 ret = btrfs_del_item(trans, dev_root, path);
                 if (ret != 0) {
-                        printk(KERN_WARNING "btrfs: delete too small dev_stats item for device %s failed %d!\n",
-                               device->name, ret);
+                        printk_in_rcu(KERN_WARNING "btrfs: delete too small dev_stats item for device %s failed %d!\n",
+                                      rcu_str_deref(device->name), ret);
                         goto out;
                 }
                 ret = 1;
@@ -4770,8 +4794,8 @@ static int update_dev_stat_item(struct btrfs_trans_handle *trans,
                 ret = btrfs_insert_empty_item(trans, dev_root, path,
                                               &key, sizeof(*ptr));
                 if (ret < 0) {
-                        printk(KERN_WARNING "btrfs: insert dev_stats item for device %s failed %d!\n",
-                               device->name, ret);
+                        printk_in_rcu(KERN_WARNING "btrfs: insert dev_stats item for device %s failed %d!\n",
+                                      rcu_str_deref(device->name), ret);
                         goto out;
                 }
         }
@@ -4823,9 +4847,9 @@ void btrfs_dev_stat_print_on_error(struct btrfs_device *dev)
 {
         if (!dev->dev_stats_valid)
                 return;
-        printk_ratelimited(KERN_ERR
+        printk_ratelimited_in_rcu(KERN_ERR
                            "btrfs: bdev %s errs: wr %u, rd %u, flush %u, corrupt %u, gen %u\n",
-                           dev->name,
+                           rcu_str_deref(dev->name),
                            btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_WRITE_ERRS),
                            btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_READ_ERRS),
                            btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_FLUSH_ERRS),
@@ -4837,8 +4861,8 @@ void btrfs_dev_stat_print_on_error(struct btrfs_device *dev)
 
 static void btrfs_dev_stat_print_on_load(struct btrfs_device *dev)
 {
-        printk(KERN_INFO "btrfs: bdev %s errs: wr %u, rd %u, flush %u, corrupt %u, gen %u\n",
-               dev->name,
+        printk_in_rcu(KERN_INFO "btrfs: bdev %s errs: wr %u, rd %u, flush %u, corrupt %u, gen %u\n",
+               rcu_str_deref(dev->name),
                btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_WRITE_ERRS),
                btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_READ_ERRS),
                btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_FLUSH_ERRS),