[v2,1/6] btrfs: Introduce a function to check if all chunks a OK for degraded rw mount
diff mbox

Message ID 20170306085855.11403-2-quwenruo@cn.fujitsu.com
State New
Headers show

Commit Message

Qu Wenruo March 6, 2017, 8:58 a.m. UTC
Introduce a new function, btrfs_check_rw_degradable(), to check if all
chunks in btrfs is OK for degraded rw mount.

It provides the new basis for accurate btrfs mount/remount and even
runtime degraded mount check other than old one-size-fit-all method.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
 fs/btrfs/volumes.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/volumes.h |  1 +
 2 files changed, 54 insertions(+)

Comments

Anand Jain March 7, 2017, 4:48 a.m. UTC | #1
On 03/06/2017 04:58 PM, Qu Wenruo wrote:
> Introduce a new function, btrfs_check_rw_degradable(), to check if all
> chunks in btrfs is OK for degraded rw mount.
>
> It provides the new basis for accurate btrfs mount/remount and even
> runtime degraded mount check other than old one-size-fit-all method.

  Looks good.
  Reviewed-by: Anand Jain <anand.jain@oracle.com>

Thanks, Anand


> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> ---
>  fs/btrfs/volumes.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/btrfs/volumes.h |  1 +
>  2 files changed, 54 insertions(+)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 7c8c7bbee197..dd9dd94d7043 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -6765,6 +6765,59 @@ int btrfs_read_sys_array(struct btrfs_fs_info *fs_info)
>  	return -EIO;
>  }
>
> +/*
> + * Check if all chunks in the fs is OK for read-write degraded mount
> + *
> + * Return true if the fs is OK to be mounted degraded read-write
> + * Return false if the fs is not OK to be mounted degraded
> + */
> +bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info)
> +{
> +	struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
> +	struct extent_map *em;
> +	u64 next_start = 0;
> +	bool ret = true;
> +
> +	read_lock(&map_tree->map_tree.lock);
> +	em = lookup_extent_mapping(&map_tree->map_tree, 0, (u64)-1);
> +	/* No chunk at all? Return false anyway */
> +	if (!em) {
> +		ret = false;
> +		goto out;
> +	}
> +	while (em) {
> +		struct map_lookup *map;
> +		int missing = 0;
> +		int max_tolerated;
> +		int i;
> +
> +		map = (struct map_lookup *) em->bdev;
> +		max_tolerated =
> +			btrfs_get_num_tolerated_disk_barrier_failures(
> +					map->type);
> +		for (i = 0; i < map->num_stripes; i++) {
> +			if (map->stripes[i].dev->missing)
> +				missing++;
> +		}
> +		if (missing > max_tolerated) {
> +			ret = false;
> +			btrfs_warn(fs_info,
> +	"chunk %llu missing %d devices, max tolerance is %d for writeble mount",
> +				   em->start, missing, max_tolerated);
> +			free_extent_map(em);
> +			goto out;
> +		}
> +		next_start = extent_map_end(em);
> +		free_extent_map(em);
> +
> +		em = lookup_extent_mapping(&map_tree->map_tree, next_start,
> +					   (u64)(-1) - next_start);
> +	}
> +out:
> +	read_unlock(&map_tree->map_tree.lock);
> +	return ret;
> +}
> +
>  int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
>  {
>  	struct btrfs_root *root = fs_info->chunk_root;
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index 59be81206dd7..db1b5ef479cf 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -538,4 +538,5 @@ struct list_head *btrfs_get_fs_uuids(void);
>  void btrfs_set_fs_info_ptr(struct btrfs_fs_info *fs_info);
>  void btrfs_reset_fs_info_ptr(struct btrfs_fs_info *fs_info);
>
> +bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info);
>  #endif
>
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Anand Jain March 8, 2017, 6:26 p.m. UTC | #2
>> Introduce a new function, btrfs_check_rw_degradable(), to check if all
>> chunks in btrfs is OK for degraded rw mount.
>>
>> It provides the new basis for accurate btrfs mount/remount and even
>> runtime degraded mount check other than old one-size-fit-all method.

   Sorry for late response. But this patch has a bug (calls free
   with the lock held) and fixed in this patch [1].
    [1]
     [PATCH] btrfs: fix btrfs_check_degradable() to free extent map
     https://patchwork.kernel.org/patch/8868761/

   the last version of this patch is here [2] and it did contain the
   above fix [1] but it missed my sign-off and change commit log
   update (sorry for that)
     [2] http://www.spinics.net/lists/linux-btrfs/msg55038.html

   Can you pls squash [1] to this patch.

   With that.

>  Looks good.
>  Reviewed-by: Anand Jain <anand.jain@oracle.com>

  While you are here, can you also consider..

-----
@@ -6843,7 +6843,7 @@ bool btrfs_check_rw_degradable(struct 
btrfs_fs_info *fs_info,
                 int max_tolerated;
                 int i;

-               map = (struct map_lookup *) em->bdev;
+               map = em->map_lookup;
                 max_tolerated =
                         btrfs_get_num_tolerated_disk_barrier_failures(
                                         map->type);
------


   Thanks, Anand
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Qu Wenruo March 9, 2017, 12:31 a.m. UTC | #3
At 03/09/2017 02:26 AM, Anand Jain wrote:
>
>
>>> Introduce a new function, btrfs_check_rw_degradable(), to check if all
>>> chunks in btrfs is OK for degraded rw mount.
>>>
>>> It provides the new basis for accurate btrfs mount/remount and even
>>> runtime degraded mount check other than old one-size-fit-all method.
>
>   Sorry for late response. But this patch has a bug (calls free
>   with the lock held) and fixed in this patch [1].
>    [1]
>     [PATCH] btrfs: fix btrfs_check_degradable() to free extent map
>     https://patchwork.kernel.org/patch/8868761/

Thanks for the patch, while in v3, the memory leak is fixed.

However I still call free with read lock hold, I'll update it in v3.
>
>   the last version of this patch is here [2] and it did contain the
>   above fix [1] but it missed my sign-off and change commit log
>   update (sorry for that)
>     [2] http://www.spinics.net/lists/linux-btrfs/msg55038.html
>
>   Can you pls squash [1] to this patch.

I'll add you signed-off-by tag in next version too.

Thanks,
Qu
>
>   With that.
>
>>  Looks good.
>>  Reviewed-by: Anand Jain <anand.jain@oracle.com>
>
>  While you are here, can you also consider..
>
> -----
> @@ -6843,7 +6843,7 @@ bool btrfs_check_rw_degradable(struct
> btrfs_fs_info *fs_info,
>                 int max_tolerated;
>                 int i;
>
> -               map = (struct map_lookup *) em->bdev;
> +               map = em->map_lookup;
>                 max_tolerated =
>                         btrfs_get_num_tolerated_disk_barrier_failures(
>                                         map->type);
> ------
>
>
>   Thanks, Anand
>
>


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Patch
diff mbox

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 7c8c7bbee197..dd9dd94d7043 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6765,6 +6765,59 @@  int btrfs_read_sys_array(struct btrfs_fs_info *fs_info)
 	return -EIO;
 }
 
+/*
+ * Check if all chunks in the fs is OK for read-write degraded mount
+ *
+ * Return true if the fs is OK to be mounted degraded read-write
+ * Return false if the fs is not OK to be mounted degraded
+ */
+bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
+	struct extent_map *em;
+	u64 next_start = 0;
+	bool ret = true;
+
+	read_lock(&map_tree->map_tree.lock);
+	em = lookup_extent_mapping(&map_tree->map_tree, 0, (u64)-1);
+	/* No chunk at all? Return false anyway */
+	if (!em) {
+		ret = false;
+		goto out;
+	}
+	while (em) {
+		struct map_lookup *map;
+		int missing = 0;
+		int max_tolerated;
+		int i;
+
+		map = (struct map_lookup *) em->bdev;
+		max_tolerated =
+			btrfs_get_num_tolerated_disk_barrier_failures(
+					map->type);
+		for (i = 0; i < map->num_stripes; i++) {
+			if (map->stripes[i].dev->missing)
+				missing++;
+		}
+		if (missing > max_tolerated) {
+			ret = false;
+			btrfs_warn(fs_info,
+	"chunk %llu missing %d devices, max tolerance is %d for writeble mount",
+				   em->start, missing, max_tolerated);
+			free_extent_map(em);
+			goto out;
+		}
+		next_start = extent_map_end(em);
+		free_extent_map(em);
+
+		em = lookup_extent_mapping(&map_tree->map_tree, next_start,
+					   (u64)(-1) - next_start);
+	}
+out:
+	read_unlock(&map_tree->map_tree.lock);
+	return ret;
+}
+
 int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
 {
 	struct btrfs_root *root = fs_info->chunk_root;
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 59be81206dd7..db1b5ef479cf 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -538,4 +538,5 @@  struct list_head *btrfs_get_fs_uuids(void);
 void btrfs_set_fs_info_ptr(struct btrfs_fs_info *fs_info);
 void btrfs_reset_fs_info_ptr(struct btrfs_fs_info *fs_info);
 
+bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info);
 #endif