Stefan Behrens
2013-Aug-15 15:11 UTC
[PATCH v8 0/8] Btrfs: introduce a tree for UUID to subvol ID mapping
Mapping UUIDs to subvolume IDs is an operation with a high effort
today. Today, the algorithm even has quadratic effort (based on the
number of existing subvolumes), which means, that it takes minutes
to send/receive a single subvolume if 10,000 subvolumes exist. But
even linear effort would be too much since it is a waste. And these
data structures to allow mapping UUIDs to subvolume IDs are created
every time a btrfs send/receive instance is started.
So the issue to address is that Btrfs send / receive does not work
as it is today when a high number of subvolumes exist.
The table below shows the time it takes on my testbox to send _one_
empty subvolume depending on the number of subvolume that exist in
the filesystem.
# of subvols | without | with
in filesystem | UUID tree | UUID tree
--------------+------------+----------
2 | 0m00.004s | 0m00.003s
1000 | 0m07.010s | 0m00.004s
2000 | 0m28.210s | 0m00.004s
3000 | 1m04.872s | 0m00.004s
4000 | 1m56.059s | 0m00.004s
5000 | 3m00.489s | 0m00.004s
6000 | 4m27.376s | 0m00.004s
7000 | 6m08.938s | 0m00.004s
8000 | 7m54.020s | 0m00.004s
9000 | 10m05.108s | 0m00.004s
10000 | 12m47.406s | 0m00.004s
11000 | 15m05.800s | 0m00.004s
12000 | 18m00.170s | 0m00.004s
13000 | 21m39.438s | 0m00.004s
14000 | 24m54.681s | 0m00.004s
15000 | 28m09.096s | 0m00.004s
16000 | 33m08.856s | 0m00.004s
17000 | 37m10.562s | 0m00.004s
18000 | 41m44.727s | 0m00.004s
19000 | 46m14.335s | 0m00.004s
20000 | 51m55.100s | 0m00.004s
21000 | 56m54.346s | 0m00.004s
22000 | 62m53.466s | 0m00.004s
23000 | 66m57.328s | 0m00.004s
24000 | 73m59.687s | 0m00.004s
25000 | 81m24.476s | 0m00.004s
26000 | 87m11.478s | 0m00.004s
27000 | 92m59.225s | 0m00.004s
Or as a chart:
http://btrfs.giantdisaster.de/Btrfs-send-recv-perf.pdf
It is much more efficient to maintain a searchable persistent data
structure in the filesystem, one that is updated whenever a
subvolume/snapshot is created and deleted, and when the received
subvolume UUID is set by the btrfs-receive tool.
Therefore kernel code is added that is able to maintain data
structures in the filesystem that allow to quickly search for a
given UUID and to retrieve the subvol ID.
Now follows the lengthy justification, why a new tree was added
instead of using the existing root tree:
The first approach was to not create another tree that holds UUID
items. Instead, the items should just go into the top root tree.
Unfortunately this confused the algorithm to assign the objectid
of subvolumes and snapshots. The reason is that
btrfs_find_free_objectid() calls btrfs_find_highest_objectid() for
the first created subvol or snapshot after mounting a filesystem,
and this function simply searches for the largest used objectid in
the root tree keys to pick the next objectid to assign. Of course,
the UUID keys have always been the ones with the highest offset
value, and the next assigned subvol ID was wastefully huge.
To use any other existing tree did not look proper. To apply a
workaround such as setting the objectid to zero in the UUID item
key and to implement collision handling would either add
limitations (in case of a btrfs_extend_item() approach to handle
the collisions) or a lot of complexity and source code (in case a
key would be looked up that is free of collisions). Adding new code
that introduces limitations is not good, and adding code that is
complex and lengthy for no good reason is also not good. That''s the
justification why a completely new tree was introduced.
v1 -> v2:
- All review comments from David Sterba, Josef Bacik and Jan Schmidt
are addressed.
The hugest change was to add a mechanism that handles the case that
the filesystem is mounted with an older kernel. Now that case is
detected when the filesystem is mounted with a newer kernel again,
and the UUID tree is updated in the background.
v2 -> v3:
- All review comments from Liu Bo are addressed:
- shrinked the size of the uuid_item.
- fixed the issue that the uuid-tree was not using the transaction
block reserve.
v3 -> v4:
- Fixed a bug. A corrupted UUID tree entry could have caused an endless
loop in the check+rescan thread.
v4 -> v5:
- On demand from multiple persons, the way was changed that a umount
waits for the completion of the uuid tree rescan thread. Now a
struct completion is used instead of a struct semaphore.
v5 -> v6:
- Iterate through the UUID tree using btrfs_next_item() when possible.
- Use the type field in the key to distinguish the UUID tree item types.
- Removed the lookup functions that are only used in the btrfs-progs
code.
v6 -> v7:
- WARN_ON_ONCE specifically returns the condition.
- Eliminate the sparse warnings that CF=-D__CHECK_ENDIAN__ produces.
- Have callers pass in the key type to the search functions and remove
the specific search functions.
v7 -> v8:
- Rebase
- Undo the changes that I had done for v5. Don''t use a completion. The
completion meant to either manually reimplement a semaphore with a
completion, or to cause bugs (the latter was the case since v5).
I changed it back to use a semaphore, this time making lockdep et al.
happy and setting the semaphore to its initial state at the end.
Stefan Behrens (8):
Btrfs: introduce a tree for items that map UUIDs to something
Btrfs: support printing UUID tree elements
Btrfs: create UUID tree if required
Btrfs: maintain subvolume items in the UUID tree
Btrfs: fill UUID tree initially
Btrfs: introduce uuid-tree-gen field
Btrfs: check UUID tree during mount if required
Btrfs: add mount option to force UUID tree checking
fs/btrfs/Makefile | 3 +-
fs/btrfs/ctree.h | 39 +++++-
fs/btrfs/disk-io.c | 58 ++++++++
fs/btrfs/extent-tree.c | 3 +
fs/btrfs/ioctl.c | 76 +++++++++--
fs/btrfs/print-tree.c | 24 ++++
fs/btrfs/super.c | 8 +-
fs/btrfs/transaction.c | 22 ++-
fs/btrfs/uuid-tree.c | 358 +++++++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/volumes.c | 258 +++++++++++++++++++++++++++++++++++
fs/btrfs/volumes.h | 2 +
11 files changed, 837 insertions(+), 14 deletions(-)
create mode 100644 fs/btrfs/uuid-tree.c
--
1.8.3.4
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Stefan Behrens
2013-Aug-15 15:11 UTC
[PATCH v8 1/8] Btrfs: introduce a tree for items that map UUIDs to something
Mapping UUIDs to subvolume IDs is an operation with a high effort
today. Today, the algorithm even has quadratic effort (based on the
number of existing subvolumes), which means, that it takes minutes
to send/receive a single subvolume if 10,000 subvolumes exist. But
even linear effort would be too much since it is a waste. And these
data structures to allow mapping UUIDs to subvolume IDs are created
every time a btrfs send/receive instance is started.
It is much more efficient to maintain a searchable persistent data
structure in the filesystem, one that is updated whenever a
subvolume/snapshot is created and deleted, and when the received
subvolume UUID is set by the btrfs-receive tool.
Therefore kernel code is added with this commit that is able to
maintain data structures in the filesystem that allow to quickly
search for a given UUID and to retrieve data that is assigned to
this UUID, like which subvolume ID is related to this UUID.
This commit adds a new tree to hold UUID-to-data mapping items. The
key of the items is the full UUID plus the key type BTRFS_UUID_KEY.
Multiple data blocks can be stored for a given UUID, a type/length/
value scheme is used.
Now follows the lengthy justification, why a new tree was added
instead of using the existing root tree:
The first approach was to not create another tree that holds UUID
items. Instead, the items should just go into the top root tree.
Unfortunately this confused the algorithm to assign the objectid
of subvolumes and snapshots. The reason is that
btrfs_find_free_objectid() calls btrfs_find_highest_objectid() for
the first created subvol or snapshot after mounting a filesystem,
and this function simply searches for the largest used objectid in
the root tree keys to pick the next objectid to assign. Of course,
the UUID keys have always been the ones with the highest offset
value, and the next assigned subvol ID was wastefully huge.
To use any other existing tree did not look proper. To apply a
workaround such as setting the objectid to zero in the UUID item
key and to implement collision handling would either add
limitations (in case of a btrfs_extend_item() approach to handle
the collisions) or a lot of complexity and source code (in case a
key would be looked up that is free of collisions). Adding new code
that introduces limitations is not good, and adding code that is
complex and lengthy for no good reason is also not good. That''s the
justification why a completely new tree was introduced.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
---
fs/btrfs/Makefile | 3 +-
fs/btrfs/ctree.h | 24 ++++++
fs/btrfs/uuid-tree.c | 235 +++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 261 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index 3932224..a550dfc 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -8,7 +8,8 @@ btrfs-y += super.o ctree.o extent-tree.o print-tree.o
root-tree.o dir-item.o \
extent_io.o volumes.o async-thread.o ioctl.o locking.o orphan.o \
export.o tree-log.o free-space-cache.o zlib.o lzo.o \
compression.o delayed-ref.o relocation.o delayed-inode.o scrub.o \
- reada.o backref.o ulist.o qgroup.o send.o dev-replace.o raid56.o
+ reada.o backref.o ulist.o qgroup.o send.o dev-replace.o raid56.o \
+ uuid-tree.o
btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o
btrfs-$(CONFIG_BTRFS_FS_CHECK_INTEGRITY) += check-integrity.o
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 0632832..ba5eef2 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -91,6 +91,9 @@ struct btrfs_ordered_sum;
/* holds quota configuration and tracking */
#define BTRFS_QUOTA_TREE_OBJECTID 8ULL
+/* for storing items that use the BTRFS_UUID_KEY* types */
+#define BTRFS_UUID_TREE_OBJECTID 9ULL
+
/* for storing balance parameters in the root tree */
#define BTRFS_BALANCE_OBJECTID -4ULL
@@ -1936,6 +1939,19 @@ struct btrfs_ioctl_defrag_range_args {
#define BTRFS_DEV_REPLACE_KEY 250
/*
+ * Stores items that allow to quickly map UUIDs to something else.
+ * These items are part of the filesystem UUID tree.
+ * The key is built like this:
+ * (UUID_upper_64_bits, BTRFS_UUID_KEY*, UUID_lower_64_bits).
+ */
+#if BTRFS_UUID_SIZE != 16
+#error "UUID items require BTRFS_UUID_SIZE == 16!"
+#endif
+#define BTRFS_UUID_KEY_SUBVOL 251 /* for UUIDs assigned to subvols */
+#define BTRFS_UUID_KEY_RECEIVED_SUBVOL 252 /* for UUIDs assigned to
+ * received subvols */
+
+/*
* string items are for debugging. They just store a short string of
* data in the FS
*/
@@ -3477,6 +3493,14 @@ void btrfs_check_and_init_root_item(struct
btrfs_root_item *item);
void btrfs_update_root_times(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
+/* uuid-tree.c */
+int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans,
+ struct btrfs_root *uuid_root, u8 *uuid, u8 type,
+ u64 subid);
+int btrfs_uuid_tree_rem(struct btrfs_trans_handle *trans,
+ struct btrfs_root *uuid_root, u8 *uuid, u8 type,
+ u64 subid);
+
/* dir-item.c */
int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir,
const char *name, int name_len);
diff --git a/fs/btrfs/uuid-tree.c b/fs/btrfs/uuid-tree.c
new file mode 100644
index 0000000..04a04fa
--- /dev/null
+++ b/fs/btrfs/uuid-tree.c
@@ -0,0 +1,235 @@
+/*
+ * Copyright (C) STRATO AG 2013. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+#include <linux/uuid.h>
+#include <asm/unaligned.h>
+#include "ctree.h"
+#include "transaction.h"
+#include "disk-io.h"
+#include "print-tree.h"
+
+
+static void btrfs_uuid_to_key(u8 *uuid, u8 type, struct btrfs_key *key)
+{
+ key->type = type;
+ key->objectid = get_unaligned_le64(uuid);
+ key->offset = get_unaligned_le64(uuid + sizeof(u64));
+}
+
+/* return -ENOENT for !found, < 0 for errors, or 0 if an item was found */
+static int btrfs_uuid_tree_lookup(struct btrfs_root *uuid_root, u8 *uuid,
+ u8 type, u64 subid)
+{
+ int ret;
+ struct btrfs_path *path = NULL;
+ struct extent_buffer *eb;
+ int slot;
+ u32 item_size;
+ unsigned long offset;
+ struct btrfs_key key;
+
+ if (WARN_ON_ONCE(!uuid_root)) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ btrfs_uuid_to_key(uuid, type, &key);
+ ret = btrfs_search_slot(NULL, uuid_root, &key, path, 0, 0);
+ if (ret < 0) {
+ goto out;
+ } else if (ret > 0) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ eb = path->nodes[0];
+ slot = path->slots[0];
+ item_size = btrfs_item_size_nr(eb, slot);
+ offset = btrfs_item_ptr_offset(eb, slot);
+ ret = -ENOENT;
+
+ if (!IS_ALIGNED(item_size, sizeof(u64))) {
+ pr_warn("btrfs: uuid item with illegal size %lu!\n",
+ (unsigned long)item_size);
+ goto out;
+ }
+ while (item_size) {
+ __le64 data;
+
+ read_extent_buffer(eb, &data, offset, sizeof(data));
+ if (le64_to_cpu(data) == subid) {
+ ret = 0;
+ break;
+ }
+ offset += sizeof(data);
+ item_size -= sizeof(data);
+ }
+
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans,
+ struct btrfs_root *uuid_root, u8 *uuid, u8 type,
+ u64 subid_cpu)
+{
+ int ret;
+ struct btrfs_path *path = NULL;
+ struct btrfs_key key;
+ struct extent_buffer *eb;
+ int slot;
+ unsigned long offset;
+ __le64 subid_le;
+
+ ret = btrfs_uuid_tree_lookup(uuid_root, uuid, type, subid_cpu);
+ if (ret != -ENOENT)
+ return ret;
+
+ if (WARN_ON_ONCE(!uuid_root)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ btrfs_uuid_to_key(uuid, type, &key);
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ ret = btrfs_insert_empty_item(trans, uuid_root, path, &key,
+ sizeof(subid_le));
+ if (ret >= 0) {
+ /* Add an item for the type for the first time */
+ eb = path->nodes[0];
+ slot = path->slots[0];
+ offset = btrfs_item_ptr_offset(eb, slot);
+ } else if (ret == -EEXIST) {
+ /*
+ * An item with that type already exists.
+ * Extend the item and store the new subid at the end.
+ */
+ btrfs_extend_item(uuid_root, path, sizeof(subid_le));
+ eb = path->nodes[0];
+ slot = path->slots[0];
+ offset = btrfs_item_ptr_offset(eb, slot);
+ offset += btrfs_item_size_nr(eb, slot) - sizeof(subid_le);
+ } else if (ret < 0) {
+ pr_warn("btrfs: insert uuid item failed %d (0x%016llx, 0x%016llx) type
%u!\n",
+ ret, (unsigned long long)key.objectid,
+ (unsigned long long)key.offset, type);
+ goto out;
+ }
+
+ ret = 0;
+ subid_le = cpu_to_le64(subid_cpu);
+ write_extent_buffer(eb, &subid_le, offset, sizeof(subid_le));
+ btrfs_mark_buffer_dirty(eb);
+
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+int btrfs_uuid_tree_rem(struct btrfs_trans_handle *trans,
+ struct btrfs_root *uuid_root, u8 *uuid, u8 type,
+ u64 subid)
+{
+ int ret;
+ struct btrfs_path *path = NULL;
+ struct btrfs_key key;
+ struct extent_buffer *eb;
+ int slot;
+ unsigned long offset;
+ u32 item_size;
+ unsigned long move_dst;
+ unsigned long move_src;
+ unsigned long move_len;
+
+ if (WARN_ON_ONCE(!uuid_root)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ btrfs_uuid_to_key(uuid, type, &key);
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ ret = btrfs_search_slot(trans, uuid_root, &key, path, -1, 1);
+ if (ret < 0) {
+ pr_warn("btrfs: error %d while searching for uuid item!\n",
+ ret);
+ goto out;
+ }
+ if (ret > 0) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ eb = path->nodes[0];
+ slot = path->slots[0];
+ offset = btrfs_item_ptr_offset(eb, slot);
+ item_size = btrfs_item_size_nr(eb, slot);
+ if (!IS_ALIGNED(item_size, sizeof(u64))) {
+ pr_warn("btrfs: uuid item with illegal size %lu!\n",
+ (unsigned long)item_size);
+ ret = -ENOENT;
+ goto out;
+ }
+ while (item_size) {
+ __le64 read_subid;
+
+ read_extent_buffer(eb, &read_subid, offset, sizeof(read_subid));
+ if (le64_to_cpu(read_subid) == subid)
+ break;
+ offset += sizeof(read_subid);
+ item_size -= sizeof(read_subid);
+ }
+
+ if (!item_size) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ item_size = btrfs_item_size_nr(eb, slot);
+ if (item_size == sizeof(subid)) {
+ ret = btrfs_del_item(trans, uuid_root, path);
+ goto out;
+ }
+
+ move_dst = offset;
+ move_src = offset + sizeof(subid);
+ move_len = item_size - (move_src - btrfs_item_ptr_offset(eb, slot));
+ memmove_extent_buffer(eb, move_dst, move_src, move_len);
+ btrfs_truncate_item(uuid_root, path, item_size - sizeof(subid), 1);
+
+out:
+ btrfs_free_path(path);
+ return ret;
+}
--
1.8.3.4
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Stefan Behrens
2013-Aug-15 15:11 UTC
[PATCH v8 2/8] Btrfs: support printing UUID tree elements
This commit adds support to print UUID tree elements to print-tree.c.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
---
fs/btrfs/print-tree.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/fs/btrfs/print-tree.c b/fs/btrfs/print-tree.c
index fe7bf4a..32022f3 100644
--- a/fs/btrfs/print-tree.c
+++ b/fs/btrfs/print-tree.c
@@ -155,6 +155,25 @@ static void print_extent_ref_v0(struct extent_buffer *eb,
int slot)
}
#endif
+static void print_uuid_item(struct extent_buffer *l, unsigned long offset,
+ u32 item_size)
+{
+ if (!IS_ALIGNED(item_size, sizeof(u64))) {
+ pr_warn("btrfs: uuid item with illegal size %lu!\n",
+ (unsigned long)item_size);
+ return;
+ }
+ while (item_size) {
+ __le64 subvol_id;
+
+ read_extent_buffer(l, &subvol_id, offset, sizeof(subvol_id));
+ printk(KERN_INFO "\t\tsubvol_id %llu\n",
+ (unsigned long long)le64_to_cpu(subvol_id));
+ item_size -= sizeof(u64);
+ offset += sizeof(u64);
+ }
+}
+
void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
{
int i;
@@ -301,6 +320,11 @@ void btrfs_print_leaf(struct btrfs_root *root, struct
extent_buffer *l)
case BTRFS_DEV_REPLACE_KEY:
printk(KERN_INFO "\t\tdev replace\n");
break;
+ case BTRFS_UUID_KEY_SUBVOL:
+ case BTRFS_UUID_KEY_RECEIVED_SUBVOL:
+ print_uuid_item(l, btrfs_item_ptr_offset(l, i),
+ btrfs_item_size_nr(l, i));
+ break;
};
}
}
--
1.8.3.4
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This tree is not created by mkfs.btrfs. Therefore when a filesystem
is mounted writable and the UUID tree does not exist, this tree is
created if required. The tree is also added to the fs_info structure
and initialized, but this commit does not yet read or write UUID tree
elements.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
---
fs/btrfs/ctree.h | 1 +
fs/btrfs/disk-io.c | 34 ++++++++++++++++++++++++++++++++++
fs/btrfs/extent-tree.c | 3 +++
fs/btrfs/volumes.c | 26 ++++++++++++++++++++++++++
fs/btrfs/volumes.h | 1 +
5 files changed, 65 insertions(+)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index ba5eef2..9e0d212 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1306,6 +1306,7 @@ struct btrfs_fs_info {
struct btrfs_root *fs_root;
struct btrfs_root *csum_root;
struct btrfs_root *quota_root;
+ struct btrfs_root *uuid_root;
/* the log root tree is a directory of all the other log roots */
struct btrfs_root *log_root_tree;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 5de9ad7..f75ccfc 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1585,6 +1585,9 @@ struct btrfs_root *btrfs_read_fs_root_no_name(struct
btrfs_fs_info *fs_info,
if (location->objectid == BTRFS_QUOTA_TREE_OBJECTID)
return fs_info->quota_root ? fs_info->quota_root :
ERR_PTR(-ENOENT);
+ if (location->objectid == BTRFS_UUID_TREE_OBJECTID)
+ return fs_info->uuid_root ? fs_info->uuid_root :
+ ERR_PTR(-ENOENT);
again:
root = btrfs_lookup_fs_root(fs_info, location->objectid);
if (root)
@@ -2043,6 +2046,12 @@ static void free_root_pointers(struct btrfs_fs_info
*info, int chunk_root)
info->quota_root->node = NULL;
info->quota_root->commit_root = NULL;
}
+ if (info->uuid_root) {
+ free_extent_buffer(info->uuid_root->node);
+ free_extent_buffer(info->uuid_root->commit_root);
+ info->uuid_root->node = NULL;
+ info->uuid_root->commit_root = NULL;
+ }
if (chunk_root) {
free_extent_buffer(info->chunk_root->node);
free_extent_buffer(info->chunk_root->commit_root);
@@ -2103,11 +2112,13 @@ int open_ctree(struct super_block *sb,
struct btrfs_root *chunk_root;
struct btrfs_root *dev_root;
struct btrfs_root *quota_root;
+ struct btrfs_root *uuid_root;
struct btrfs_root *log_tree_root;
int ret;
int err = -EINVAL;
int num_backups_tried = 0;
int backup_index = 0;
+ bool create_uuid_tree = false;
tree_root = fs_info->tree_root = btrfs_alloc_root(fs_info);
chunk_root = fs_info->chunk_root = btrfs_alloc_root(fs_info);
@@ -2702,6 +2713,18 @@ retry_root_backup:
fs_info->quota_root = quota_root;
}
+ location.objectid = BTRFS_UUID_TREE_OBJECTID;
+ uuid_root = btrfs_read_tree_root(tree_root, &location);
+ if (IS_ERR(uuid_root)) {
+ ret = PTR_ERR(uuid_root);
+ if (ret != -ENOENT)
+ goto recovery_tree_root;
+ create_uuid_tree = true;
+ } else {
+ uuid_root->track_dirty = 1;
+ fs_info->uuid_root = uuid_root;
+ }
+
fs_info->generation = generation;
fs_info->last_trans_committed = generation;
@@ -2888,6 +2911,17 @@ retry_root_backup:
btrfs_qgroup_rescan_resume(fs_info);
+ if (create_uuid_tree) {
+ pr_info("btrfs: creating UUID tree\n");
+ ret = btrfs_create_uuid_tree(fs_info);
+ if (ret) {
+ pr_warn("btrfs: failed to create the UUID tree %d\n",
+ ret);
+ close_ctree(tree_root);
+ return ret;
+ }
+ }
+
return 0;
fail_qgroup:
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index c1b2dd7..e065086 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4361,6 +4361,9 @@ static struct btrfs_block_rsv *get_block_rsv(
if (root == root->fs_info->csum_root && trans->adding_csums)
block_rsv = trans->block_rsv;
+ if (root == root->fs_info->uuid_root)
+ block_rsv = trans->block_rsv;
+
if (!block_rsv)
block_rsv = root->block_rsv;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 44abd15..b99d3f4 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3432,6 +3432,32 @@ int btrfs_cancel_balance(struct btrfs_fs_info *fs_info)
return 0;
}
+int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_trans_handle *trans;
+ struct btrfs_root *tree_root = fs_info->tree_root;
+ struct btrfs_root *uuid_root;
+
+ /*
+ * 1 - root node
+ * 1 - root item
+ */
+ trans = btrfs_start_transaction(tree_root, 2);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
+
+ uuid_root = btrfs_create_tree(trans, fs_info,
+ BTRFS_UUID_TREE_OBJECTID);
+ if (IS_ERR(uuid_root)) {
+ btrfs_abort_transaction(trans, tree_root,
+ PTR_ERR(uuid_root));
+ return PTR_ERR(uuid_root);
+ }
+
+ fs_info->uuid_root = uuid_root;
+
+ return btrfs_commit_transaction(trans, tree_root);
+}
/*
* shrinking a device means finding all of the device extents past
* the new size, and then following the back refs to the chunks.
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 08c44d9..7071b298 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -322,6 +322,7 @@ int btrfs_resume_balance_async(struct btrfs_fs_info
*fs_info);
int btrfs_recover_balance(struct btrfs_fs_info *fs_info);
int btrfs_pause_balance(struct btrfs_fs_info *fs_info);
int btrfs_cancel_balance(struct btrfs_fs_info *fs_info);
+int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info);
int btrfs_chunk_readonly(struct btrfs_root *root, u64 chunk_offset);
int find_free_dev_extent(struct btrfs_trans_handle *trans,
struct btrfs_device *device, u64 num_bytes,
--
1.8.3.4
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Stefan Behrens
2013-Aug-15 15:11 UTC
[PATCH v8 4/8] Btrfs: maintain subvolume items in the UUID tree
When a new subvolume or snapshot is created, a new UUID item is added
to the UUID tree. Such items are removed when the subvolume is deleted.
The ioctl to set the received subvolume UUID is also touched and will
now also add this received UUID into the UUID tree together with the
ID of the subvolume. The latter is also done when read-only snapshots
are created which inherit all the send/receive information from the
parent subvolume.
User mode programs use the BTRFS_IOC_TREE_SEARCH ioctl to search and
read in the UUID tree.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
---
fs/btrfs/ctree.h | 1 +
fs/btrfs/ioctl.c | 76 +++++++++++++++++++++++++++++++++++++++++++-------
fs/btrfs/transaction.c | 20 ++++++++++++-
3 files changed, 86 insertions(+), 11 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 9e0d212..9a99c66 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3721,6 +3721,7 @@ extern const struct dentry_operations
btrfs_dentry_operations;
long btrfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
void btrfs_update_iflags(struct inode *inode);
void btrfs_inherit_iflags(struct inode *inode, struct inode *dir);
+int btrfs_is_empty_uuid(u8 *uuid);
int btrfs_defrag_file(struct inode *inode, struct file *file,
struct btrfs_ioctl_defrag_range_args *range,
u64 newer_than, unsigned long max_pages);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 2312c0f..3e36626 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -367,6 +367,13 @@ static noinline int btrfs_ioctl_fitrim(struct file *file,
void __user *arg)
return 0;
}
+int btrfs_is_empty_uuid(u8 *uuid)
+{
+ static char empty_uuid[BTRFS_UUID_SIZE] = {0};
+
+ return !memcmp(uuid, empty_uuid, BTRFS_UUID_SIZE);
+}
+
static noinline int create_subvol(struct inode *dir,
struct dentry *dentry,
char *name, int namelen,
@@ -400,7 +407,7 @@ static noinline int create_subvol(struct inode *dir,
* of create_snapshot().
*/
ret = btrfs_subvolume_reserve_metadata(root, &block_rsv,
- 7, &qgroup_reserved, false);
+ 8, &qgroup_reserved, false);
if (ret)
return ret;
@@ -522,9 +529,14 @@ static noinline int create_subvol(struct inode *dir,
ret = btrfs_add_root_ref(trans, root->fs_info->tree_root,
objectid, root->root_key.objectid,
btrfs_ino(dir), index, name, namelen);
-
BUG_ON(ret);
+ ret = btrfs_uuid_tree_add(trans, root->fs_info->uuid_root,
+ root_item.uuid, BTRFS_UUID_KEY_SUBVOL,
+ objectid);
+ if (ret)
+ btrfs_abort_transaction(trans, root, ret);
+
fail:
trans->block_rsv = NULL;
trans->bytes_reserved = 0;
@@ -577,9 +589,10 @@ static int create_snapshot(struct btrfs_root *root, struct
inode *dir,
* 1 - root item
* 2 - root ref/backref
* 1 - root of snapshot
+ * 1 - UUID item
*/
ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,
- &pending_snapshot->block_rsv, 7,
+ &pending_snapshot->block_rsv, 8,
&pending_snapshot->qgroup_reserved,
false);
if (ret)
@@ -2218,6 +2231,27 @@ static noinline int btrfs_ioctl_snap_destroy(struct file
*file,
goto out_end_trans;
}
}
+
+ ret = btrfs_uuid_tree_rem(trans, root->fs_info->uuid_root,
+ dest->root_item.uuid, BTRFS_UUID_KEY_SUBVOL,
+ dest->root_key.objectid);
+ if (ret && ret != -ENOENT) {
+ btrfs_abort_transaction(trans, root, ret);
+ err = ret;
+ goto out_end_trans;
+ }
+ if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) {
+ ret = btrfs_uuid_tree_rem(trans, root->fs_info->uuid_root,
+ dest->root_item.received_uuid,
+ BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+ dest->root_key.objectid);
+ if (ret && ret != -ENOENT) {
+ btrfs_abort_transaction(trans, root, ret);
+ err = ret;
+ goto out_end_trans;
+ }
+ }
+
out_end_trans:
trans->block_rsv = NULL;
trans->bytes_reserved = 0;
@@ -2429,7 +2463,6 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root,
void __user *arg)
struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
int ret = 0;
char *s_uuid = NULL;
- char empty_uuid[BTRFS_UUID_SIZE] = {0};
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
@@ -2438,7 +2471,7 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root,
void __user *arg)
if (IS_ERR(di_args))
return PTR_ERR(di_args);
- if (memcmp(empty_uuid, di_args->uuid, BTRFS_UUID_SIZE) != 0)
+ if (!btrfs_is_empty_uuid(di_args->uuid))
s_uuid = di_args->uuid;
mutex_lock(&fs_devices->device_list_mutex);
@@ -4275,6 +4308,7 @@ static long btrfs_ioctl_set_received_subvol(struct file
*file,
struct btrfs_trans_handle *trans;
struct timespec ct = CURRENT_TIME;
int ret = 0;
+ int received_uuid_changed;
ret = mnt_want_write_file(file);
if (ret < 0)
@@ -4304,7 +4338,11 @@ static long btrfs_ioctl_set_received_subvol(struct file
*file,
goto out;
}
- trans = btrfs_start_transaction(root, 1);
+ /*
+ * 1 - root item
+ * 2 - uuid items (received uuid + subvol uuid)
+ */
+ trans = btrfs_start_transaction(root, 3);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
trans = NULL;
@@ -4315,6 +4353,14 @@ static long btrfs_ioctl_set_received_subvol(struct file
*file,
sa->rtime.sec = ct.tv_sec;
sa->rtime.nsec = ct.tv_nsec;
+ received_uuid_changed = memcmp(root_item->received_uuid, sa->uuid,
+ BTRFS_UUID_SIZE);
+ if (received_uuid_changed &&
+ !btrfs_is_empty_uuid(root_item->received_uuid))
+ btrfs_uuid_tree_rem(trans, root->fs_info->uuid_root,
+ root_item->received_uuid,
+ BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+ root->root_key.objectid);
memcpy(root_item->received_uuid, sa->uuid, BTRFS_UUID_SIZE);
btrfs_set_root_stransid(root_item, sa->stransid);
btrfs_set_root_rtransid(root_item, sa->rtransid);
@@ -4327,12 +4373,22 @@ static long btrfs_ioctl_set_received_subvol(struct file
*file,
&root->root_key, &root->root_item);
if (ret < 0) {
btrfs_end_transaction(trans, root);
- trans = NULL;
goto out;
- } else {
- ret = btrfs_commit_transaction(trans, root);
- if (ret < 0)
+ }
+ if (received_uuid_changed && !btrfs_is_empty_uuid(sa->uuid)) {
+ ret = btrfs_uuid_tree_add(trans, root->fs_info->uuid_root,
+ sa->uuid,
+ BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+ root->root_key.objectid);
+ if (ret < 0 && ret != -EEXIST) {
+ btrfs_abort_transaction(trans, root, ret);
goto out;
+ }
+ }
+ ret = btrfs_commit_transaction(trans, root);
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, root, ret);
+ goto out;
}
ret = copy_to_user(arg, sa, sizeof(*sa));
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index ea8d522..06ae6ef 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1311,8 +1311,26 @@ static noinline int create_pending_snapshot(struct
btrfs_trans_handle *trans,
dentry->d_name.len * 2);
parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
- if (ret)
+ if (ret) {
+ btrfs_abort_transaction(trans, root, ret);
+ goto fail;
+ }
+ ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root, new_uuid.b,
+ BTRFS_UUID_KEY_SUBVOL, objectid);
+ if (ret) {
btrfs_abort_transaction(trans, root, ret);
+ goto fail;
+ }
+ if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
+ ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root,
+ new_root_item->received_uuid,
+ BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+ objectid);
+ if (ret && ret != -EEXIST) {
+ btrfs_abort_transaction(trans, root, ret);
+ goto fail;
+ }
+ }
fail:
pending->error = ret;
dir_item_existed:
--
1.8.3.4
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When the UUID tree is initially created, a task is spawned that
walks through the root tree. For each found subvolume root_item,
the uuid and received_uuid entries in the UUID tree are added.
This is such a quick operation so that in case somebody wants
to unmount the filesystem while the task is still running, the
unmount is delayed until the UUID tree building task is finished.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
---
fs/btrfs/ctree.h | 3 ++
fs/btrfs/disk-io.c | 7 +++
fs/btrfs/volumes.c | 151 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 160 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 9a99c66..e6b71ad 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -23,6 +23,7 @@
#include <linux/highmem.h>
#include <linux/fs.h>
#include <linux/rwsem.h>
+#include <linux/semaphore.h>
#include <linux/completion.h>
#include <linux/backing-dev.h>
#include <linux/wait.h>
@@ -1647,6 +1648,8 @@ struct btrfs_fs_info {
struct btrfs_dev_replace dev_replace;
atomic_t mutually_exclusive_operation_running;
+
+ struct semaphore uuid_tree_rescan_sem;
};
/*
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index f75ccfc..d9ff76e 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -31,6 +31,7 @@
#include <linux/migrate.h>
#include <linux/ratelimit.h>
#include <linux/uuid.h>
+#include <linux/semaphore.h>
#include <asm/unaligned.h>
#include "compat.h"
#include "ctree.h"
@@ -2295,6 +2296,7 @@ int open_ctree(struct super_block *sb,
init_rwsem(&fs_info->extent_commit_sem);
init_rwsem(&fs_info->cleanup_work_sem);
init_rwsem(&fs_info->subvol_sem);
+ sema_init(&fs_info->uuid_tree_rescan_sem, 1);
fs_info->dev_replace.lock_owner = 0;
atomic_set(&fs_info->dev_replace.nesting_level, 0);
mutex_init(&fs_info->dev_replace.lock_finishing_cancel_unmount);
@@ -3552,6 +3554,11 @@ int close_ctree(struct btrfs_root *root)
fs_info->closing = 1;
smp_mb();
+ /* wait for the uuid_scan task to finish */
+ down(&fs_info->uuid_tree_rescan_sem);
+ /* avoid complains from lockdep et al., set sem back to initial state */
+ up(&fs_info->uuid_tree_rescan_sem);
+
/* pause restriper - we want to resume on mount */
btrfs_pause_balance(fs_info);
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b99d3f4..8e0aeef 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -26,6 +26,7 @@
#include <linux/ratelimit.h>
#include <linux/kthread.h>
#include <linux/raid/pq.h>
+#include <linux/semaphore.h>
#include <asm/div64.h>
#include "compat.h"
#include "ctree.h"
@@ -3432,11 +3433,146 @@ int btrfs_cancel_balance(struct btrfs_fs_info *fs_info)
return 0;
}
+static int btrfs_uuid_scan_kthread(void *data)
+{
+ struct btrfs_fs_info *fs_info = data;
+ struct btrfs_root *root = fs_info->tree_root;
+ struct btrfs_key key;
+ struct btrfs_key max_key;
+ struct btrfs_path *path = NULL;
+ int ret = 0;
+ struct extent_buffer *eb;
+ int slot;
+ struct btrfs_root_item root_item;
+ u32 item_size;
+ struct btrfs_trans_handle *trans;
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ key.objectid = 0;
+ key.type = BTRFS_ROOT_ITEM_KEY;
+ key.offset = 0;
+
+ max_key.objectid = (u64)-1;
+ max_key.type = BTRFS_ROOT_ITEM_KEY;
+ max_key.offset = (u64)-1;
+
+ path->keep_locks = 1;
+
+ while (1) {
+ ret = btrfs_search_forward(root, &key, &max_key, path, 0);
+ if (ret) {
+ if (ret > 0)
+ ret = 0;
+ break;
+ }
+
+ if (key.type != BTRFS_ROOT_ITEM_KEY ||
+ (key.objectid < BTRFS_FIRST_FREE_OBJECTID &&
+ key.objectid != BTRFS_FS_TREE_OBJECTID) ||
+ key.objectid > BTRFS_LAST_FREE_OBJECTID)
+ goto skip;
+
+ eb = path->nodes[0];
+ slot = path->slots[0];
+ item_size = btrfs_item_size_nr(eb, slot);
+ if (item_size < sizeof(root_item))
+ goto skip;
+
+ trans = NULL;
+ read_extent_buffer(eb, &root_item,
+ btrfs_item_ptr_offset(eb, slot),
+ (int)sizeof(root_item));
+ if (btrfs_root_refs(&root_item) == 0)
+ goto skip;
+ if (!btrfs_is_empty_uuid(root_item.uuid)) {
+ /*
+ * 1 - subvol uuid item
+ * 1 - received_subvol uuid item
+ */
+ trans = btrfs_start_transaction(fs_info->uuid_root, 2);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ break;
+ }
+ ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root,
+ root_item.uuid,
+ BTRFS_UUID_KEY_SUBVOL,
+ key.objectid);
+ if (ret < 0) {
+ pr_warn("btrfs: uuid_tree_add failed %d\n",
+ ret);
+ btrfs_end_transaction(trans,
+ fs_info->uuid_root);
+ break;
+ }
+ }
+
+ if (!btrfs_is_empty_uuid(root_item.received_uuid)) {
+ if (!trans) {
+ /* 1 - received_subvol uuid item */
+ trans = btrfs_start_transaction(
+ fs_info->uuid_root, 1);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ break;
+ }
+ }
+ ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root,
+ root_item.received_uuid,
+ BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+ key.objectid);
+ if (ret < 0) {
+ pr_warn("btrfs: uuid_tree_add failed %d\n",
+ ret);
+ btrfs_end_transaction(trans,
+ fs_info->uuid_root);
+ break;
+ }
+ }
+
+ if (trans) {
+ ret = btrfs_end_transaction(trans, fs_info->uuid_root);
+ if (ret)
+ break;
+ }
+
+skip:
+ btrfs_release_path(path);
+ if (key.offset < (u64)-1) {
+ key.offset++;
+ } else if (key.type < BTRFS_ROOT_ITEM_KEY) {
+ key.offset = 0;
+ key.type = BTRFS_ROOT_ITEM_KEY;
+ } else if (key.objectid < (u64)-1) {
+ key.offset = 0;
+ key.type = BTRFS_ROOT_ITEM_KEY;
+ key.objectid++;
+ } else {
+ break;
+ }
+ cond_resched();
+ }
+
+out:
+ btrfs_free_path(path);
+ if (ret)
+ pr_warn("btrfs: btrfs_uuid_scan_kthread failed %d\n", ret);
+ up(&fs_info->uuid_tree_rescan_sem);
+ return 0;
+}
+
int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info)
{
struct btrfs_trans_handle *trans;
struct btrfs_root *tree_root = fs_info->tree_root;
struct btrfs_root *uuid_root;
+ struct task_struct *task;
+ int ret;
/*
* 1 - root node
@@ -3456,8 +3592,21 @@ int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info)
fs_info->uuid_root = uuid_root;
- return btrfs_commit_transaction(trans, tree_root);
+ ret = btrfs_commit_transaction(trans, tree_root);
+ if (ret)
+ return ret;
+
+ down(&fs_info->uuid_tree_rescan_sem);
+ task = kthread_run(btrfs_uuid_scan_kthread, fs_info, "btrfs-uuid");
+ if (IS_ERR(task)) {
+ pr_warn("btrfs: failed to start uuid_scan task\n");
+ up(&fs_info->uuid_tree_rescan_sem);
+ return PTR_ERR(task);
+ }
+
+ return 0;
}
+
/*
* shrinking a device means finding all of the device extents past
* the new size, and then following the back refs to the chunks.
--
1.8.3.4
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In order to be able to detect the case that a filesystem is mounted
with an old kernel, add a uuid-tree-gen field like the free space
cache is doing it. It is part of the super block and written with
each commit. Old kernels do not know this field and don''t update it.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
---
fs/btrfs/ctree.h | 5 ++++-
fs/btrfs/transaction.c | 1 +
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index e6b71ad..f71d254 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -482,9 +482,10 @@ struct btrfs_super_block {
char label[BTRFS_LABEL_SIZE];
__le64 cache_generation;
+ __le64 uuid_tree_generation;
/* future expansion */
- __le64 reserved[31];
+ __le64 reserved[30];
u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
struct btrfs_root_backup super_roots[BTRFS_NUM_BACKUP_ROOTS];
} __attribute__ ((__packed__));
@@ -2893,6 +2894,8 @@ BTRFS_SETGET_STACK_FUNCS(super_csum_type, struct
btrfs_super_block,
BTRFS_SETGET_STACK_FUNCS(super_cache_generation, struct btrfs_super_block,
cache_generation, 64);
BTRFS_SETGET_STACK_FUNCS(super_magic, struct btrfs_super_block, magic, 64);
+BTRFS_SETGET_STACK_FUNCS(super_uuid_tree_generation, struct btrfs_super_block,
+ uuid_tree_generation, 64);
static inline int btrfs_super_csum_size(struct btrfs_super_block *s)
{
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 06ae6ef..32eb543 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1380,6 +1380,7 @@ static void update_super_roots(struct btrfs_root *root)
super->root_level = root_item->level;
if (btrfs_test_opt(root, SPACE_CACHE))
super->cache_generation = root_item->generation;
+ super->uuid_tree_generation = root_item->generation;
}
int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
--
1.8.3.4
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Stefan Behrens
2013-Aug-15 15:11 UTC
[PATCH v8 7/8] Btrfs: check UUID tree during mount if required
If the filesystem was mounted with an old kernel that was not
aware of the UUID tree, this is detected by looking at the
uuid_tree_generation field of the superblock (similar to how
the free space cache is doing it). If a mismatch is detected
at mount time, a thread is started that does two things:
1. Iterate through the UUID tree, check each entry, delete those
entries that are not valid anymore (i.e., the subvol does not
exist anymore or the value changed).
2. Iterate through the root tree, for each found subvolume, add
the UUID tree entries for the subvolume (if they are not
already there).
This mechanism is also used to handle and repair errors that
happened during the initial creation and filling of the tree.
The update of the uuid_tree_generation field (which indicates
that the state of the UUID tree is up to date) is blocked until
all create and repair operations are successfully completed.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
---
fs/btrfs/ctree.h | 4 ++
fs/btrfs/disk-io.c | 18 +++++++-
fs/btrfs/transaction.c | 3 +-
fs/btrfs/uuid-tree.c | 123 +++++++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/volumes.c | 83 +++++++++++++++++++++++++++++++++
fs/btrfs/volumes.h | 1 +
6 files changed, 230 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index f71d254..edd74da 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1651,6 +1651,7 @@ struct btrfs_fs_info {
atomic_t mutually_exclusive_operation_running;
struct semaphore uuid_tree_rescan_sem;
+ unsigned int update_uuid_tree_gen:1;
};
/*
@@ -3507,6 +3508,9 @@ int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans,
int btrfs_uuid_tree_rem(struct btrfs_trans_handle *trans,
struct btrfs_root *uuid_root, u8 *uuid, u8 type,
u64 subid);
+int btrfs_uuid_tree_iterate(struct btrfs_fs_info *fs_info,
+ int (*check_func)(struct btrfs_fs_info *, u8 *, u8,
+ u64));
/* dir-item.c */
int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index d9ff76e..fc3d95f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2119,7 +2119,8 @@ int open_ctree(struct super_block *sb,
int err = -EINVAL;
int num_backups_tried = 0;
int backup_index = 0;
- bool create_uuid_tree = false;
+ bool create_uuid_tree;
+ bool check_uuid_tree;
tree_root = fs_info->tree_root = btrfs_alloc_root(fs_info);
chunk_root = fs_info->chunk_root = btrfs_alloc_root(fs_info);
@@ -2722,9 +2723,13 @@ retry_root_backup:
if (ret != -ENOENT)
goto recovery_tree_root;
create_uuid_tree = true;
+ check_uuid_tree = false;
} else {
uuid_root->track_dirty = 1;
fs_info->uuid_root = uuid_root;
+ create_uuid_tree = false;
+ check_uuid_tree + generation !=
btrfs_super_uuid_tree_generation(disk_super);
}
fs_info->generation = generation;
@@ -2922,6 +2927,17 @@ retry_root_backup:
close_ctree(tree_root);
return ret;
}
+ } else if (check_uuid_tree) {
+ pr_info("btrfs: checking UUID tree\n");
+ ret = btrfs_check_uuid_tree(fs_info);
+ if (ret) {
+ pr_warn("btrfs: failed to check the UUID tree %d\n",
+ ret);
+ close_ctree(tree_root);
+ return ret;
+ }
+ } else {
+ fs_info->update_uuid_tree_gen = 1;
}
return 0;
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 32eb543..649d3a5 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1380,7 +1380,8 @@ static void update_super_roots(struct btrfs_root *root)
super->root_level = root_item->level;
if (btrfs_test_opt(root, SPACE_CACHE))
super->cache_generation = root_item->generation;
- super->uuid_tree_generation = root_item->generation;
+ if (root->fs_info->update_uuid_tree_gen)
+ super->uuid_tree_generation = root_item->generation;
}
int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
diff --git a/fs/btrfs/uuid-tree.c b/fs/btrfs/uuid-tree.c
index 04a04fa..dd0dea3 100644
--- a/fs/btrfs/uuid-tree.c
+++ b/fs/btrfs/uuid-tree.c
@@ -233,3 +233,126 @@ out:
btrfs_free_path(path);
return ret;
}
+
+static int btrfs_uuid_iter_rem(struct btrfs_root *uuid_root, u8 *uuid, u8 type,
+ u64 subid)
+{
+ struct btrfs_trans_handle *trans;
+ int ret;
+
+ /* 1 - for the uuid item */
+ trans = btrfs_start_transaction(uuid_root, 1);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ goto out;
+ }
+
+ ret = btrfs_uuid_tree_rem(trans, uuid_root, uuid, type, subid);
+ btrfs_end_transaction(trans, uuid_root);
+
+out:
+ return ret;
+}
+
+int btrfs_uuid_tree_iterate(struct btrfs_fs_info *fs_info,
+ int (*check_func)(struct btrfs_fs_info *, u8 *, u8,
+ u64))
+{
+ struct btrfs_root *root = fs_info->uuid_root;
+ struct btrfs_key key;
+ struct btrfs_key max_key;
+ struct btrfs_path *path;
+ int ret = 0;
+ struct extent_buffer *leaf;
+ int slot;
+ u32 item_size;
+ unsigned long offset;
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ key.objectid = 0;
+ key.type = 0;
+ key.offset = 0;
+ max_key.objectid = (u64)-1;
+ max_key.type = (u8)-1;
+ max_key.offset = (u64)-1;
+
+again_search_slot:
+ path->keep_locks = 1;
+ ret = btrfs_search_forward(root, &key, &max_key, path, 0);
+ if (ret) {
+ if (ret > 0)
+ ret = 0;
+ goto out;
+ }
+
+ while (1) {
+ cond_resched();
+ leaf = path->nodes[0];
+ slot = path->slots[0];
+ btrfs_item_key_to_cpu(leaf, &key, slot);
+
+ if (key.type != BTRFS_UUID_KEY_SUBVOL &&
+ key.type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
+ goto skip;
+
+ offset = btrfs_item_ptr_offset(leaf, slot);
+ item_size = btrfs_item_size_nr(leaf, slot);
+ if (!IS_ALIGNED(item_size, sizeof(u64))) {
+ pr_warn("btrfs: uuid item with illegal size %lu!\n",
+ (unsigned long)item_size);
+ goto skip;
+ }
+ while (item_size) {
+ u8 uuid[BTRFS_UUID_SIZE];
+ __le64 subid_le;
+ u64 subid_cpu;
+
+ put_unaligned_le64(key.objectid, uuid);
+ put_unaligned_le64(key.offset, uuid + sizeof(u64));
+ read_extent_buffer(leaf, &subid_le, offset,
+ sizeof(subid_le));
+ subid_cpu = le64_to_cpu(subid_le);
+ ret = check_func(fs_info, uuid, key.type, subid_cpu);
+ if (ret < 0)
+ goto out;
+ if (ret > 0) {
+ btrfs_release_path(path);
+ ret = btrfs_uuid_iter_rem(root, uuid, key.type,
+ subid_cpu);
+ if (ret == 0) {
+ /*
+ * this might look inefficient, but the
+ * justification is that it is an
+ * exception that check_func returns 1,
+ * and that in the regular case only one
+ * entry per UUID exists.
+ */
+ goto again_search_slot;
+ }
+ if (ret < 0 && ret != -ENOENT)
+ goto out;
+ }
+ item_size -= sizeof(subid_le);
+ offset += sizeof(subid_le);
+ }
+
+skip:
+ ret = btrfs_next_item(root, path);
+ if (ret == 0)
+ continue;
+ else if (ret > 0)
+ ret = 0;
+ break;
+ }
+
+out:
+ btrfs_free_path(path);
+ if (ret)
+ pr_warn("btrfs: btrfs_uuid_tree_iterate failed %d\n", ret);
+ return 0;
+}
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 8e0aeef..a4d196d 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3562,10 +3562,76 @@ out:
btrfs_free_path(path);
if (ret)
pr_warn("btrfs: btrfs_uuid_scan_kthread failed %d\n", ret);
+ else
+ fs_info->update_uuid_tree_gen = 1;
up(&fs_info->uuid_tree_rescan_sem);
return 0;
}
+/*
+ * Callback for btrfs_uuid_tree_iterate().
+ * returns:
+ * 0 check succeeded, the entry is not outdated.
+ * < 0 if an error occured.
+ * > 0 if the check failed, which means the caller shall remove the entry.
+ */
+static int btrfs_check_uuid_tree_entry(struct btrfs_fs_info *fs_info,
+ u8 *uuid, u8 type, u64 subid)
+{
+ struct btrfs_key key;
+ int ret = 0;
+ struct btrfs_root *subvol_root;
+
+ if (type != BTRFS_UUID_KEY_SUBVOL &&
+ type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
+ goto out;
+
+ key.objectid = subid;
+ key.type = BTRFS_ROOT_ITEM_KEY;
+ key.offset = (u64)-1;
+ subvol_root = btrfs_read_fs_root_no_name(fs_info, &key);
+ if (IS_ERR(subvol_root)) {
+ ret = PTR_ERR(subvol_root);
+ if (ret == -ENOENT)
+ ret = 1;
+ goto out;
+ }
+
+ switch (type) {
+ case BTRFS_UUID_KEY_SUBVOL:
+ if (memcmp(uuid, subvol_root->root_item.uuid, BTRFS_UUID_SIZE))
+ ret = 1;
+ break;
+ case BTRFS_UUID_KEY_RECEIVED_SUBVOL:
+ if (memcmp(uuid, subvol_root->root_item.received_uuid,
+ BTRFS_UUID_SIZE))
+ ret = 1;
+ break;
+ }
+
+out:
+ return ret;
+}
+
+static int btrfs_uuid_rescan_kthread(void *data)
+{
+ struct btrfs_fs_info *fs_info = (struct btrfs_fs_info *)data;
+ int ret;
+
+ /*
+ * 1st step is to iterate through the existing UUID tree and
+ * to delete all entries that contain outdated data.
+ * 2nd step is to add all missing entries to the UUID tree.
+ */
+ ret = btrfs_uuid_tree_iterate(fs_info, btrfs_check_uuid_tree_entry);
+ if (ret < 0) {
+ pr_warn("btrfs: iterating uuid_tree failed %d\n", ret);
+ up(&fs_info->uuid_tree_rescan_sem);
+ return ret;
+ }
+ return btrfs_uuid_scan_kthread(data);
+}
+
int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info)
{
struct btrfs_trans_handle *trans;
@@ -3599,6 +3665,7 @@ int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info)
down(&fs_info->uuid_tree_rescan_sem);
task = kthread_run(btrfs_uuid_scan_kthread, fs_info, "btrfs-uuid");
if (IS_ERR(task)) {
+ /* fs_info->update_uuid_tree_gen remains 0 in all error case */
pr_warn("btrfs: failed to start uuid_scan task\n");
up(&fs_info->uuid_tree_rescan_sem);
return PTR_ERR(task);
@@ -3607,6 +3674,22 @@ int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info)
return 0;
}
+int btrfs_check_uuid_tree(struct btrfs_fs_info *fs_info)
+{
+ struct task_struct *task;
+
+ down(&fs_info->uuid_tree_rescan_sem);
+ task = kthread_run(btrfs_uuid_rescan_kthread, fs_info,
"btrfs-uuid");
+ if (IS_ERR(task)) {
+ /* fs_info->update_uuid_tree_gen remains 0 in all error case */
+ pr_warn("btrfs: failed to start uuid_rescan task\n");
+ up(&fs_info->uuid_tree_rescan_sem);
+ return PTR_ERR(task);
+ }
+
+ return 0;
+}
+
/*
* shrinking a device means finding all of the device extents past
* the new size, and then following the back refs to the chunks.
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 7071b298..d98b942 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -323,6 +323,7 @@ int btrfs_recover_balance(struct btrfs_fs_info *fs_info);
int btrfs_pause_balance(struct btrfs_fs_info *fs_info);
int btrfs_cancel_balance(struct btrfs_fs_info *fs_info);
int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info);
+int btrfs_check_uuid_tree(struct btrfs_fs_info *fs_info);
int btrfs_chunk_readonly(struct btrfs_root *root, u64 chunk_offset);
int find_free_dev_extent(struct btrfs_trans_handle *trans,
struct btrfs_device *device, u64 num_bytes,
--
1.8.3.4
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Stefan Behrens
2013-Aug-15 15:11 UTC
[PATCH v8 8/8] Btrfs: add mount option to force UUID tree checking
This should never be needed, but since all functions are there
to check and rebuild the UUID tree, a mount option is added that
allows to force this check and rebuild procedure.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
---
fs/btrfs/ctree.h | 1 +
fs/btrfs/disk-io.c | 3 ++-
fs/btrfs/super.c | 8 +++++++-
3 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index edd74da..c420dc9 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1991,6 +1991,7 @@ struct btrfs_ioctl_defrag_range_args {
#define BTRFS_MOUNT_CHECK_INTEGRITY (1 << 20)
#define BTRFS_MOUNT_CHECK_INTEGRITY_INCLUDING_EXTENT_DATA (1 << 21)
#define BTRFS_MOUNT_PANIC_ON_FATAL_ERROR (1 << 22)
+#define BTRFS_MOUNT_RESCAN_UUID_TREE (1 << 23)
#define BTRFS_DEFAULT_COMMIT_INTERVAL (30)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index fc3d95f..b7bc4ec 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2927,7 +2927,8 @@ retry_root_backup:
close_ctree(tree_root);
return ret;
}
- } else if (check_uuid_tree) {
+ } else if (check_uuid_tree ||
+ btrfs_test_opt(tree_root, RESCAN_UUID_TREE)) {
pr_info("btrfs: checking UUID tree\n");
ret = btrfs_check_uuid_tree(fs_info);
if (ret) {
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 1967903..0eea577 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -320,7 +320,7 @@ enum {
Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_inode_cache,
Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
Opt_check_integrity, Opt_check_integrity_including_extent_data,
- Opt_check_integrity_print_mask, Opt_fatal_errors,
+ Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
Opt_commit_interval,
Opt_err,
};
@@ -361,6 +361,7 @@ static match_table_t tokens = {
{Opt_check_integrity, "check_int"},
{Opt_check_integrity_including_extent_data, "check_int_data"},
{Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
+ {Opt_rescan_uuid_tree, "rescan_uuid_tree"},
{Opt_fatal_errors, "fatal_errors=%s"},
{Opt_commit_interval, "commit=%d"},
{Opt_err, NULL},
@@ -571,6 +572,9 @@ int btrfs_parse_options(struct btrfs_root *root, char
*options)
case Opt_space_cache:
btrfs_set_opt(info->mount_opt, SPACE_CACHE);
break;
+ case Opt_rescan_uuid_tree:
+ btrfs_set_opt(info->mount_opt, RESCAN_UUID_TREE);
+ break;
case Opt_no_space_cache:
printk(KERN_INFO "btrfs: disabling disk space caching\n");
btrfs_clear_opt(info->mount_opt, SPACE_CACHE);
@@ -978,6 +982,8 @@ static int btrfs_show_options(struct seq_file *seq, struct
dentry *dentry)
seq_puts(seq, ",space_cache");
else
seq_puts(seq, ",nospace_cache");
+ if (btrfs_test_opt(root, RESCAN_UUID_TREE))
+ seq_puts(seq, ",rescan_uuid_tree");
if (btrfs_test_opt(root, CLEAR_CACHE))
seq_puts(seq, ",clear_cache");
if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
--
1.8.3.4
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