Btrfs: use rcu to protect device->name
[platform/adaptation/renesas_rcar/renesas_kernel.git] / fs / btrfs / volumes.c
index 7782020..8a3d259 100644 (file)
@@ -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),