| Message ID | 1351617376-5208-1-git-send-email-sbehrens@giantdisaster.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Patch looks ok, juste one thing that caught my attention (and does not block
the patch)
a bit of context:
1224 if (fs_info->fs_devices->rw_devices == 0) {
1225 ret = -EACCES;
1226 goto restore;
1227 }
> + if (fs_info->fs_devices->missing_devices >
> + fs_info->num_tolerated_disk_barrier_failures &&
> + !(*flags & MS_RDONLY)) {
> + printk(KERN_WARNING
> + "Btrfs: too many missing devices, writeable remount is not allowed\n");
> + ret = -EACCES;
the error code is strange, but it also appears above and has been there for
ages. We're not checking any sort of permissions so this looks confusing,
probably EINVAL or EPERM ?
> + goto restore;
> + }
> +
> if (btrfs_super_log_root(fs_info->super_copy) != 0) {
> ret = -EINVAL;
> goto restore;
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diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 7cda519..29de7c1 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2503,6 +2503,13 @@ retry_root_backup: } fs_info->num_tolerated_disk_barrier_failures = btrfs_calc_num_tolerated_disk_barrier_failures(fs_info); + if (fs_info->fs_devices->missing_devices > + fs_info->num_tolerated_disk_barrier_failures && + !(sb->s_flags & MS_RDONLY)) { + printk(KERN_WARNING + "Btrfs: too many missing devices, writeable mount is not allowed\n"); + goto fail_block_groups; + } fs_info->cleaner_kthread = kthread_run(cleaner_kthread, tree_root, "btrfs-cleaner"); diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 915ac14..acd2df8 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1226,6 +1226,15 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data) goto restore; } + if (fs_info->fs_devices->missing_devices > + fs_info->num_tolerated_disk_barrier_failures && + !(*flags & MS_RDONLY)) { + printk(KERN_WARNING + "Btrfs: too many missing devices, writeable remount is not allowed\n"); + ret = -EACCES; + goto restore; + } + if (btrfs_super_log_root(fs_info->super_copy) != 0) { ret = -EINVAL; goto restore;
The current behavior is to allow mounting or remounting a filesystem writeable in degraded mode if at least one writeable device is present. The next failed write access to a missing device which is above the tolerance of the configured level of redundancy results in an read-only enforcement. Even without this, the next time barrier_all_devices() is called and more devices are missing than tolerable, the switch to read-only mode takes place. In order to behave predictably and to provide proper feedback to the user at mount time, this patch compares the number of missing devices with the number of devices that are tolerated to be missing according to the configured RAID level. If more devices are missing than tolerated, e.g. if two devices are missing in case of RAID1, only a read-only mount and remount is allowed. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> --- fs/btrfs/disk-io.c | 7 +++++++ fs/btrfs/super.c | 9 +++++++++ 2 files changed, 16 insertions(+)