On 08/03/2018 09:33 PM, Nikolay Borisov wrote:
On 3.08.2018 15:45, Anand Jain wrote:
Its a logical bug if we hit fs_devices::num_devices == 1 and if the
replace is running because, as fs_devices::num_devices counts the in memory
devices, so it should include the replace target which is running as
indicated by the flag. If this happens return the -EINVAL back.
Suggested-by: Nikolay Borisov <nbori...@suse.com>
Signed-off-by: Anand Jain <anand.j...@oracle.com>
---
Hi,
As it fixes the BUG_ON I have spun a new patch for this.
Instead of -EINVAL should we use ASSERT?
fs/btrfs/volumes.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 7359596ac8eb..ed2399caff80 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1855,9 +1855,11 @@ void btrfs_assign_next_active_device(struct btrfs_device
*device,
}
/* Returns btrfs_fs_devices::num_devices minus replace device if any */
-static u64 btrfs_num_devices(struct btrfs_fs_info *fs_info)
+static int btrfs_num_devices(struct btrfs_fs_info *fs_info, u64 *num_devices)
Why do you resort to this travesty of returning the value in an input
parameter? Having the function return int, assuming that we will always
have a positive device num and in case of an error return a negative
value. In the worst case when we get to see a btrfs fs consisting of 2
billion devices then we can start worrying that an int here won't do it.
Its theoretically wrong. I wonder if David is OK with this? Will wait
for his comments.
{
- u64 num_devices = fs_info->fs_devices->num_devices;
+ int ret = 0;
+
+ *num_devices = fs_info->fs_devices->num_devices;
/*
* balance and replace co-exists in a scenario as below..
@@ -1867,12 +1869,13 @@ static u64 btrfs_num_devices(struct btrfs_fs_info
*fs_info)
*/
btrfs_dev_replace_read_lock(&fs_info->dev_replace);
if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace)) {
- BUG_ON(num_devices < 1);
- num_devices--;
+ if (*num_devices < 1)
+ ret = -EINVAL;
+ (*num_devices)--;
}
btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
- return num_devices;
+ return ret;
}
int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
@@ -1886,7 +1889,12 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const
char *device_path,
mutex_lock(&uuid_mutex);
- num_devices = btrfs_num_devices(fs_info);
+ ret = btrfs_num_devices(fs_info, &num_devices);
+ if (ret) {
The canonical form, used across the whole code base of btrfs, for
checking for an error is 'if (ret <0)' as such please stick to it in
this and all future patches.
Not a big deal will fix.
(I have a vague recollection this is not the first time I have given you
this feedback)
+ btrfs_err(fs_info, "logical bug num_devices %llu < 0",
+ num_devices);
+ return ret;
+ }
ret = btrfs_check_raid_min_devices(fs_info, num_devices - 1);
if (ret)
@@ -3755,7 +3763,12 @@ int btrfs_balance(struct btrfs_fs_info *fs_info,
}
}
- num_devices = btrfs_num_devices(fs_info);
+ ret = btrfs_num_devices(fs_info, &num_devices);
+ if (ret) {
ditto
ok.
Thanks, Anand
+ btrfs_err(fs_info, "hits a logical bug num_devices %llu < 0",
+ num_devices);
+ return ret;
+ }
allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE | BTRFS_BLOCK_GROUP_DUP;
if (num_devices > 1)
--
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