btrfs: Round down values which are written for total_bytes_size

We got an internal report about a file system not wanting to mount
following 99e3ecfcb9f4 ("Btrfs: add more validation checks for
superblock").

BTRFS error (device sdb1): super_total_bytes 1000203816960 mismatch with
fs_devices total_rw_bytes 1000203820544

Subtracting the numbers we get a difference of less than a 4kb. Upon
closer inspection it became apparent that mkfs actually rounds down the
size of the device to a multiple of sector size. However, the same
cannot be said for various functions which modify the total size and are
called from btrfs_balance as well as when adding a new device. So this
patch ensures that values being saved into on-disk data structures are
always rounded down to a multiple of sectorsize.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index b31515a2ef71061e49a3a931e31f0a264f576a73..15a77e64dc2082295dbe3e07f3b2f05516b62cb4 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1556,6 +1556,7 @@ static inline void btrfs_set_device_total_bytes(struct extent_buffer *eb,
 {
        BUILD_BUG_ON(sizeof(u64) !=
                     sizeof(((struct btrfs_dev_item *)0))->total_bytes);
+       WARN_ON(!IS_ALIGNED(val, eb->fs_info->sectorsize));
        btrfs_set_64(eb, s, offsetof(struct btrfs_dev_item, total_bytes), val);
 }
 

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index fa3c6412be724eb0b8c0f6f9988d0975d72c67fd..2090245e8f06fbd33cd680ef7cca42f18227e499 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2385,7 +2385,8 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
        device->io_width = fs_info->sectorsize;
        device->io_align = fs_info->sectorsize;
        device->sector_size = fs_info->sectorsize;
-       device->total_bytes = i_size_read(bdev->bd_inode);
+       device->total_bytes = round_down(i_size_read(bdev->bd_inode),
+                                        fs_info->sectorsize);
        device->disk_total_bytes = device->total_bytes;
        device->commit_total_bytes = device->total_bytes;
        device->fs_info = fs_info;
@@ -2422,7 +2423,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 
        tmp = btrfs_super_total_bytes(fs_info->super_copy);
        btrfs_set_super_total_bytes(fs_info->super_copy,
-                                   tmp + device->total_bytes);
+               round_down(tmp + device->total_bytes, fs_info->sectorsize));
 
        tmp = btrfs_super_num_devices(fs_info->super_copy);
        btrfs_set_super_num_devices(fs_info->super_copy, tmp + 1);
@@ -2685,6 +2686,8 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
        if (!device->writeable)
                return -EACCES;
 
+       new_size = round_down(new_size, fs_info->sectorsize);
+
        mutex_lock(&fs_info->chunk_mutex);
        old_total = btrfs_super_total_bytes(super_copy);
        diff = new_size - device->total_bytes;
@@ -2697,7 +2700,8 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
 
        fs_devices = fs_info->fs_devices;
 
-       btrfs_set_super_total_bytes(super_copy, old_total + diff);
+       btrfs_set_super_total_bytes(super_copy,
+                       round_down(old_total + diff, fs_info->sectorsize));
        device->fs_devices->total_rw_bytes += diff;
 
        btrfs_device_set_total_bytes(device, new_size);
@@ -4387,7 +4391,10 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
        struct btrfs_super_block *super_copy = fs_info->super_copy;
        u64 old_total = btrfs_super_total_bytes(super_copy);
        u64 old_size = btrfs_device_get_total_bytes(device);
-       u64 diff = old_size - new_size;
+       u64 diff;
+
+       new_size = round_down(new_size, fs_info->sectorsize);
+       diff = old_size - new_size;
 
        if (device->is_tgtdev_for_dev_replace)
                return -EINVAL;
@@ -4514,7 +4521,8 @@ again:
                              &fs_info->fs_devices->resized_devices);
 
        WARN_ON(diff > old_total);
-       btrfs_set_super_total_bytes(super_copy, old_total - diff);
+       btrfs_set_super_total_bytes(super_copy,
+                       round_down(old_total - diff, fs_info->sectorsize));
        mutex_unlock(&fs_info->chunk_mutex);
 
        /* Now btrfs_update_device() will change the on-disk size. */