Re: [PATCH 1/2] btrfs: Do per-chunk degrade mode check at mount time

[Anand Jain]

Hi Qu,

On 09/17/2015 09:48 AM, Qu Wenruo wrote:

To Anand Jain,

Any feedback on this method to allow single chunk still be degraded
mountable?

It should be much better than allowing degraded mount for any missing
device case.


yeah. this changes the way missing devices are counted and its more fine 
grained. makes sense to me.




Thanks,
Qu

Qu Wenruo wrote on 2015/09/16 11:43 +0800:

Btrfs supports different raid profile for meta/data/sys, and as
different profile support different tolerated missing device, it's
better to check if it can be mounted degraded at a per-chunk base.

So this patch will add check for read_one_chunk() against its profile,
other than checking it against with the lowest duplication profile.

Reported-by: Zhao Lei 
Reported-by: Anand Jain 
Signed-off-by: Qu Wenruo 
---
  fs/btrfs/volumes.c | 17 +
  1 file changed, 17 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 644e070..3272187 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6164,12 +6164,15 @@ static int read_one_chunk(struct btrfs_root
*root, struct btrfs_key *key,
struct btrfs_chunk *chunk)
  {
  struct btrfs_mapping_tree *map_tree = >fs_info->mapping_tree;
+struct super_block *sb = root->fs_info->sb;
  struct map_lookup *map;
  struct extent_map *em;
  u64 logical;
  u64 length;
  u64 devid;
  u8 uuid[BTRFS_UUID_SIZE];
+int missing = 0;
+int max_tolerated;
  int num_stripes;
  int ret;
  int i;
@@ -6238,7 +6241,21 @@ static int read_one_chunk(struct btrfs_root
*root, struct btrfs_key *key,
  btrfs_warn(root->fs_info, "devid %llu uuid %pU is missing",
  devid, uuid);
  }
+if (map->stripes[i].dev->missing)
+missing++;
  map->stripes[i].dev->in_fs_metadata = 1;
+
+}
+
+/* XXX: Why the function name is SO LONG?! */
+max_tolerated =
+btrfs_get_num_tolerated_disk_barrier_failures(map->type);
+if (missing > max_tolerated && !(sb->s_flags & MS_RDONLY)) {
+free_extent_map(em);
+btrfs_error(root->fs_info, -EIO,
+"missing device(%d) exceeds the limit(%d), writeable
mount is not allowed\n",


 \n is not required.

Thanks, Anand


+missing, max_tolerated);
+return -EIO;
  }

  write_lock(_tree->map_tree.lock);


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Re: [PATCH 1/2] btrfs: Do per-chunk degrade mode check at mount time

[Qu Wenruo]

To Anand Jain,

Any feedback on this method to allow single chunk still be degraded 
mountable?


It should be much better than allowing degraded mount for any missing 
device case.


Thanks,
Qu

Qu Wenruo wrote on 2015/09/16 11:43 +0800:

Btrfs supports different raid profile for meta/data/sys, and as
different profile support different tolerated missing device, it's
better to check if it can be mounted degraded at a per-chunk base.

So this patch will add check for read_one_chunk() against its profile,
other than checking it against with the lowest duplication profile.

Reported-by: Zhao Lei 
Reported-by: Anand Jain 
Signed-off-by: Qu Wenruo 
---
  fs/btrfs/volumes.c | 17 +
  1 file changed, 17 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 644e070..3272187 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6164,12 +6164,15 @@ static int read_one_chunk(struct btrfs_root *root, 
struct btrfs_key *key,
  struct btrfs_chunk *chunk)
  {
struct btrfs_mapping_tree *map_tree = >fs_info->mapping_tree;
+   struct super_block *sb = root->fs_info->sb;
struct map_lookup *map;
struct extent_map *em;
u64 logical;
u64 length;
u64 devid;
u8 uuid[BTRFS_UUID_SIZE];
+   int missing = 0;
+   int max_tolerated;
int num_stripes;
int ret;
int i;
@@ -6238,7 +6241,21 @@ static int read_one_chunk(struct btrfs_root *root, 
struct btrfs_key *key,
btrfs_warn(root->fs_info, "devid %llu uuid %pU is 
missing",
devid, uuid);
}
+   if (map->stripes[i].dev->missing)
+   missing++;
map->stripes[i].dev->in_fs_metadata = 1;
+
+   }
+
+   /* XXX: Why the function name is SO LONG?! */
+   max_tolerated =
+   btrfs_get_num_tolerated_disk_barrier_failures(map->type);
+   if (missing > max_tolerated && !(sb->s_flags & MS_RDONLY)) {
+   free_extent_map(em);
+   btrfs_error(root->fs_info, -EIO,
+   "missing device(%d) exceeds the limit(%d), writeable mount 
is not allowed\n",
+   missing, max_tolerated);
+   return -EIO;
}

write_lock(_tree->map_tree.lock);


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[PATCH 1/2] btrfs: Do per-chunk degrade mode check at mount time

[Qu Wenruo]

Btrfs supports different raid profile for meta/data/sys, and as
different profile support different tolerated missing device, it's
better to check if it can be mounted degraded at a per-chunk base.

So this patch will add check for read_one_chunk() against its profile,
other than checking it against with the lowest duplication profile.

Reported-by: Zhao Lei 
Reported-by: Anand Jain 
Signed-off-by: Qu Wenruo 
---
 fs/btrfs/volumes.c | 17 +
 1 file changed, 17 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 644e070..3272187 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6164,12 +6164,15 @@ static int read_one_chunk(struct btrfs_root *root, 
struct btrfs_key *key,
  struct btrfs_chunk *chunk)
 {
struct btrfs_mapping_tree *map_tree = >fs_info->mapping_tree;
+   struct super_block *sb = root->fs_info->sb;
struct map_lookup *map;
struct extent_map *em;
u64 logical;
u64 length;
u64 devid;
u8 uuid[BTRFS_UUID_SIZE];
+   int missing = 0;
+   int max_tolerated;
int num_stripes;
int ret;
int i;
@@ -6238,7 +6241,21 @@ static int read_one_chunk(struct btrfs_root *root, 
struct btrfs_key *key,
btrfs_warn(root->fs_info, "devid %llu uuid %pU is 
missing",
devid, uuid);
}
+   if (map->stripes[i].dev->missing)
+   missing++;
map->stripes[i].dev->in_fs_metadata = 1;
+
+   }
+
+   /* XXX: Why the function name is SO LONG?! */
+   max_tolerated =
+   btrfs_get_num_tolerated_disk_barrier_failures(map->type);
+   if (missing > max_tolerated && !(sb->s_flags & MS_RDONLY)) {
+   free_extent_map(em);
+   btrfs_error(root->fs_info, -EIO,
+   "missing device(%d) exceeds the limit(%d), writeable 
mount is not allowed\n",
+   missing, max_tolerated);
+   return -EIO;
}
 
write_lock(_tree->map_tree.lock);
-- 
2.5.2

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