* [PATCH v3 RESENT 1/2] btrfs: Add support to do stack item key operation
@ 2015-10-22 0:42 Qu Wenruo
2015-10-22 0:42 ` [PATCH v3 RESENT 2/2] btrfs: qgroup: Don't copy extent buffer to do qgroup rescan Qu Wenruo
0 siblings, 1 reply; 4+ messages in thread
From: Qu Wenruo @ 2015-10-22 0:42 UTC (permalink / raw)
To: dsterba, linux-btrfs
Normal btrfs_item_key_to_cpu() will need extent buffer to do it, and
there is not stack version to handle in memory leaf.
Add btrfs_stack_item_key_to_cpu() function for such operation, which
will provide the basis for later qgroup fix.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
v2:
Change the char* parameter to struct btrfs_header *, as a leaf always
has a header.
v3:
Fix a bug caused in type change of stack_leaf.
---
fs/btrfs/ctree.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 938efe3..b824fe2 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2683,6 +2683,17 @@ static inline void btrfs_item_key(struct extent_buffer *eb,
read_eb_member(eb, item, struct btrfs_item, key, disk_key);
}
+static inline void btrfs_stack_item_key(struct btrfs_header *stack_leaf,
+ struct btrfs_disk_key *disk_key,
+ int nr)
+{
+ unsigned long item_offset = btrfs_item_nr_offset(nr);
+ struct btrfs_item *item;
+
+ item = (struct btrfs_item *)((char *)(stack_leaf) + item_offset);
+ memcpy(disk_key, &item->key, sizeof(*disk_key));
+}
+
static inline void btrfs_set_item_key(struct extent_buffer *eb,
struct btrfs_disk_key *disk_key, int nr)
{
@@ -2785,6 +2796,15 @@ static inline void btrfs_item_key_to_cpu(struct extent_buffer *eb,
btrfs_disk_key_to_cpu(key, &disk_key);
}
+static inline void btrfs_stack_item_key_to_cpu(struct btrfs_header *stack_leaf,
+ struct btrfs_key *key,
+ int nr)
+{
+ struct btrfs_disk_key disk_key;
+ btrfs_stack_item_key(stack_leaf, &disk_key, nr);
+ btrfs_disk_key_to_cpu(key, &disk_key);
+}
+
static inline void btrfs_dir_item_key_to_cpu(struct extent_buffer *eb,
struct btrfs_dir_item *item,
struct btrfs_key *key)
--
2.6.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v3 RESENT 2/2] btrfs: qgroup: Don't copy extent buffer to do qgroup rescan
2015-10-22 0:42 [PATCH v3 RESENT 1/2] btrfs: Add support to do stack item key operation Qu Wenruo
@ 2015-10-22 0:42 ` Qu Wenruo
2015-10-22 8:16 ` Filipe Manana
0 siblings, 1 reply; 4+ messages in thread
From: Qu Wenruo @ 2015-10-22 0:42 UTC (permalink / raw)
To: dsterba, linux-btrfs
Ancient qgroup code call memcpy() on a extent buffer and use it for leaf
iteration.
As extent buffer contains lock, pointers to pages, it's never sane to do
such copy.
The following bug may be caused by this insane operation:
[92098.841309] general protection fault: 0000 [#1] SMP
[92098.841338] Modules linked in: ...
[92098.841814] CPU: 1 PID: 24655 Comm: kworker/u4:12 Not tainted
4.3.0-rc1 #1
[92098.841868] Workqueue: btrfs-qgroup-rescan btrfs_qgroup_rescan_helper
[btrfs]
[92098.842261] Call Trace:
[92098.842277] [<ffffffffc035a5d8>] ? read_extent_buffer+0xb8/0x110
[btrfs]
[92098.842304] [<ffffffffc0396d00>] ? btrfs_find_all_roots+0x60/0x70
[btrfs]
[92098.842329] [<ffffffffc039af3d>]
btrfs_qgroup_rescan_worker+0x28d/0x5a0 [btrfs]
Where btrfs_qgroup_rescan_worker+0x28d is btrfs_disk_key_to_cpu(),
called in reading key from the memcpied extent_buffer.
This patch will read the whole leaf into memory, and use newly
introduced stack function to do qgroup rescan.
Reported-by: Stephane Lesimple <stephane_btrfs@lesimple.fr>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
v2:
Follow the parameter change in previous patch.
v3:
None
---
fs/btrfs/qgroup.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index e9ace09..6a83a40 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -2183,11 +2183,11 @@ void assert_qgroups_uptodate(struct btrfs_trans_handle *trans)
*/
static int
qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
- struct btrfs_trans_handle *trans,
- struct extent_buffer *scratch_leaf)
+ struct btrfs_trans_handle *trans, char *stack_leaf)
{
struct btrfs_key found;
struct ulist *roots = NULL;
+ struct btrfs_header *header;
struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem);
u64 num_bytes;
int slot;
@@ -2224,13 +2224,15 @@ qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
fs_info->qgroup_rescan_progress.objectid = found.objectid + 1;
btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
- memcpy(scratch_leaf, path->nodes[0], sizeof(*scratch_leaf));
+ read_extent_buffer(path->nodes[0], stack_leaf, 0,
+ fs_info->extent_root->nodesize);
+ header = (struct btrfs_header *)stack_leaf;
slot = path->slots[0];
btrfs_release_path(path);
mutex_unlock(&fs_info->qgroup_rescan_lock);
- for (; slot < btrfs_header_nritems(scratch_leaf); ++slot) {
- btrfs_item_key_to_cpu(scratch_leaf, &found, slot);
+ for (; slot < btrfs_stack_header_nritems(header); ++slot) {
+ btrfs_stack_item_key_to_cpu(header, &found, slot);
if (found.type != BTRFS_EXTENT_ITEM_KEY &&
found.type != BTRFS_METADATA_ITEM_KEY)
continue;
@@ -2261,15 +2263,15 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
qgroup_rescan_work);
struct btrfs_path *path;
struct btrfs_trans_handle *trans = NULL;
- struct extent_buffer *scratch_leaf = NULL;
+ char *stack_leaf = NULL;
int err = -ENOMEM;
int ret = 0;
path = btrfs_alloc_path();
if (!path)
goto out;
- scratch_leaf = kmalloc(sizeof(*scratch_leaf), GFP_NOFS);
- if (!scratch_leaf)
+ stack_leaf = kmalloc(fs_info->extent_root->nodesize, GFP_NOFS);
+ if (!stack_leaf)
goto out;
err = 0;
@@ -2283,7 +2285,7 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
err = -EINTR;
} else {
err = qgroup_rescan_leaf(fs_info, path, trans,
- scratch_leaf);
+ stack_leaf);
}
if (err > 0)
btrfs_commit_transaction(trans, fs_info->fs_root);
@@ -2292,7 +2294,7 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
}
out:
- kfree(scratch_leaf);
+ kfree(stack_leaf);
btrfs_free_path(path);
mutex_lock(&fs_info->qgroup_rescan_lock);
--
2.6.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v3 RESENT 2/2] btrfs: qgroup: Don't copy extent buffer to do qgroup rescan
2015-10-22 0:42 ` [PATCH v3 RESENT 2/2] btrfs: qgroup: Don't copy extent buffer to do qgroup rescan Qu Wenruo
@ 2015-10-22 8:16 ` Filipe Manana
2015-10-22 8:45 ` Qu Wenruo
0 siblings, 1 reply; 4+ messages in thread
From: Filipe Manana @ 2015-10-22 8:16 UTC (permalink / raw)
To: Qu Wenruo; +Cc: dsterba@suse.cz, linux-btrfs@vger.kernel.org
On Thu, Oct 22, 2015 at 1:42 AM, Qu Wenruo <quwenruo@cn.fujitsu.com> wrote:
> Ancient qgroup code call memcpy() on a extent buffer and use it for leaf
> iteration.
>
> As extent buffer contains lock, pointers to pages, it's never sane to do
> such copy.
>
> The following bug may be caused by this insane operation:
> [92098.841309] general protection fault: 0000 [#1] SMP
> [92098.841338] Modules linked in: ...
> [92098.841814] CPU: 1 PID: 24655 Comm: kworker/u4:12 Not tainted
> 4.3.0-rc1 #1
> [92098.841868] Workqueue: btrfs-qgroup-rescan btrfs_qgroup_rescan_helper
> [btrfs]
> [92098.842261] Call Trace:
> [92098.842277] [<ffffffffc035a5d8>] ? read_extent_buffer+0xb8/0x110
> [btrfs]
> [92098.842304] [<ffffffffc0396d00>] ? btrfs_find_all_roots+0x60/0x70
> [btrfs]
> [92098.842329] [<ffffffffc039af3d>]
> btrfs_qgroup_rescan_worker+0x28d/0x5a0 [btrfs]
>
> Where btrfs_qgroup_rescan_worker+0x28d is btrfs_disk_key_to_cpu(),
> called in reading key from the memcpied extent_buffer.
>
> This patch will read the whole leaf into memory, and use newly
> introduced stack function to do qgroup rescan.
Hi Qu,
Instead of introducing more new functions, why not clone the extent
buffer (btrfs_clone_extent_buffer) and then use it the
regular/existing functions? Iow, the same as we do in backref walking,
should make the change much smaller than it is.
thanks
>
> Reported-by: Stephane Lesimple <stephane_btrfs@lesimple.fr>
> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> ---
> v2:
> Follow the parameter change in previous patch.
> v3:
> None
> ---
> fs/btrfs/qgroup.c | 22 ++++++++++++----------
> 1 file changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index e9ace09..6a83a40 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -2183,11 +2183,11 @@ void assert_qgroups_uptodate(struct btrfs_trans_handle *trans)
> */
> static int
> qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
> - struct btrfs_trans_handle *trans,
> - struct extent_buffer *scratch_leaf)
> + struct btrfs_trans_handle *trans, char *stack_leaf)
> {
> struct btrfs_key found;
> struct ulist *roots = NULL;
> + struct btrfs_header *header;
> struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem);
> u64 num_bytes;
> int slot;
> @@ -2224,13 +2224,15 @@ qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
> fs_info->qgroup_rescan_progress.objectid = found.objectid + 1;
>
> btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
> - memcpy(scratch_leaf, path->nodes[0], sizeof(*scratch_leaf));
> + read_extent_buffer(path->nodes[0], stack_leaf, 0,
> + fs_info->extent_root->nodesize);
> + header = (struct btrfs_header *)stack_leaf;
> slot = path->slots[0];
> btrfs_release_path(path);
> mutex_unlock(&fs_info->qgroup_rescan_lock);
>
> - for (; slot < btrfs_header_nritems(scratch_leaf); ++slot) {
> - btrfs_item_key_to_cpu(scratch_leaf, &found, slot);
> + for (; slot < btrfs_stack_header_nritems(header); ++slot) {
> + btrfs_stack_item_key_to_cpu(header, &found, slot);
> if (found.type != BTRFS_EXTENT_ITEM_KEY &&
> found.type != BTRFS_METADATA_ITEM_KEY)
> continue;
> @@ -2261,15 +2263,15 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
> qgroup_rescan_work);
> struct btrfs_path *path;
> struct btrfs_trans_handle *trans = NULL;
> - struct extent_buffer *scratch_leaf = NULL;
> + char *stack_leaf = NULL;
> int err = -ENOMEM;
> int ret = 0;
>
> path = btrfs_alloc_path();
> if (!path)
> goto out;
> - scratch_leaf = kmalloc(sizeof(*scratch_leaf), GFP_NOFS);
> - if (!scratch_leaf)
> + stack_leaf = kmalloc(fs_info->extent_root->nodesize, GFP_NOFS);
> + if (!stack_leaf)
> goto out;
>
> err = 0;
> @@ -2283,7 +2285,7 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
> err = -EINTR;
> } else {
> err = qgroup_rescan_leaf(fs_info, path, trans,
> - scratch_leaf);
> + stack_leaf);
> }
> if (err > 0)
> btrfs_commit_transaction(trans, fs_info->fs_root);
> @@ -2292,7 +2294,7 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
> }
>
> out:
> - kfree(scratch_leaf);
> + kfree(stack_leaf);
> btrfs_free_path(path);
>
> mutex_lock(&fs_info->qgroup_rescan_lock);
> --
> 2.6.1
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Filipe David Manana,
"Reasonable men adapt themselves to the world.
Unreasonable men adapt the world to themselves.
That's why all progress depends on unreasonable men."
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v3 RESENT 2/2] btrfs: qgroup: Don't copy extent buffer to do qgroup rescan
2015-10-22 8:16 ` Filipe Manana
@ 2015-10-22 8:45 ` Qu Wenruo
0 siblings, 0 replies; 4+ messages in thread
From: Qu Wenruo @ 2015-10-22 8:45 UTC (permalink / raw)
To: fdmanana; +Cc: dsterba@suse.cz, linux-btrfs@vger.kernel.org
Filipe Manana wrote on 2015/10/22 09:16 +0100:
> On Thu, Oct 22, 2015 at 1:42 AM, Qu Wenruo <quwenruo@cn.fujitsu.com> wrote:
>> Ancient qgroup code call memcpy() on a extent buffer and use it for leaf
>> iteration.
>>
>> As extent buffer contains lock, pointers to pages, it's never sane to do
>> such copy.
>>
>> The following bug may be caused by this insane operation:
>> [92098.841309] general protection fault: 0000 [#1] SMP
>> [92098.841338] Modules linked in: ...
>> [92098.841814] CPU: 1 PID: 24655 Comm: kworker/u4:12 Not tainted
>> 4.3.0-rc1 #1
>> [92098.841868] Workqueue: btrfs-qgroup-rescan btrfs_qgroup_rescan_helper
>> [btrfs]
>> [92098.842261] Call Trace:
>> [92098.842277] [<ffffffffc035a5d8>] ? read_extent_buffer+0xb8/0x110
>> [btrfs]
>> [92098.842304] [<ffffffffc0396d00>] ? btrfs_find_all_roots+0x60/0x70
>> [btrfs]
>> [92098.842329] [<ffffffffc039af3d>]
>> btrfs_qgroup_rescan_worker+0x28d/0x5a0 [btrfs]
>>
>> Where btrfs_qgroup_rescan_worker+0x28d is btrfs_disk_key_to_cpu(),
>> called in reading key from the memcpied extent_buffer.
>>
>> This patch will read the whole leaf into memory, and use newly
>> introduced stack function to do qgroup rescan.
>
> Hi Qu,
>
> Instead of introducing more new functions, why not clone the extent
> buffer (btrfs_clone_extent_buffer) and then use it the
> regular/existing functions? Iow, the same as we do in backref walking,
> should make the change much smaller than it is.
>
> thanks
>
Thanks Filipe,
I didn't know there is such a nice function.
And it's setting EXTENT_BUFFER_DUMMY, so it should be quite safe for the
use case.
Thanks for your advice a lot!
Qu
>>
>> Reported-by: Stephane Lesimple <stephane_btrfs@lesimple.fr>
>> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
>> ---
>> v2:
>> Follow the parameter change in previous patch.
>> v3:
>> None
>> ---
>> fs/btrfs/qgroup.c | 22 ++++++++++++----------
>> 1 file changed, 12 insertions(+), 10 deletions(-)
>>
>> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
>> index e9ace09..6a83a40 100644
>> --- a/fs/btrfs/qgroup.c
>> +++ b/fs/btrfs/qgroup.c
>> @@ -2183,11 +2183,11 @@ void assert_qgroups_uptodate(struct btrfs_trans_handle *trans)
>> */
>> static int
>> qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
>> - struct btrfs_trans_handle *trans,
>> - struct extent_buffer *scratch_leaf)
>> + struct btrfs_trans_handle *trans, char *stack_leaf)
>> {
>> struct btrfs_key found;
>> struct ulist *roots = NULL;
>> + struct btrfs_header *header;
>> struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem);
>> u64 num_bytes;
>> int slot;
>> @@ -2224,13 +2224,15 @@ qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
>> fs_info->qgroup_rescan_progress.objectid = found.objectid + 1;
>>
>> btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
>> - memcpy(scratch_leaf, path->nodes[0], sizeof(*scratch_leaf));
>> + read_extent_buffer(path->nodes[0], stack_leaf, 0,
>> + fs_info->extent_root->nodesize);
>> + header = (struct btrfs_header *)stack_leaf;
>> slot = path->slots[0];
>> btrfs_release_path(path);
>> mutex_unlock(&fs_info->qgroup_rescan_lock);
>>
>> - for (; slot < btrfs_header_nritems(scratch_leaf); ++slot) {
>> - btrfs_item_key_to_cpu(scratch_leaf, &found, slot);
>> + for (; slot < btrfs_stack_header_nritems(header); ++slot) {
>> + btrfs_stack_item_key_to_cpu(header, &found, slot);
>> if (found.type != BTRFS_EXTENT_ITEM_KEY &&
>> found.type != BTRFS_METADATA_ITEM_KEY)
>> continue;
>> @@ -2261,15 +2263,15 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
>> qgroup_rescan_work);
>> struct btrfs_path *path;
>> struct btrfs_trans_handle *trans = NULL;
>> - struct extent_buffer *scratch_leaf = NULL;
>> + char *stack_leaf = NULL;
>> int err = -ENOMEM;
>> int ret = 0;
>>
>> path = btrfs_alloc_path();
>> if (!path)
>> goto out;
>> - scratch_leaf = kmalloc(sizeof(*scratch_leaf), GFP_NOFS);
>> - if (!scratch_leaf)
>> + stack_leaf = kmalloc(fs_info->extent_root->nodesize, GFP_NOFS);
>> + if (!stack_leaf)
>> goto out;
>>
>> err = 0;
>> @@ -2283,7 +2285,7 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
>> err = -EINTR;
>> } else {
>> err = qgroup_rescan_leaf(fs_info, path, trans,
>> - scratch_leaf);
>> + stack_leaf);
>> }
>> if (err > 0)
>> btrfs_commit_transaction(trans, fs_info->fs_root);
>> @@ -2292,7 +2294,7 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
>> }
>>
>> out:
>> - kfree(scratch_leaf);
>> + kfree(stack_leaf);
>> btrfs_free_path(path);
>>
>> mutex_lock(&fs_info->qgroup_rescan_lock);
>> --
>> 2.6.1
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2015-10-22 8:45 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2015-10-22 0:42 [PATCH v3 RESENT 1/2] btrfs: Add support to do stack item key operation Qu Wenruo
2015-10-22 0:42 ` [PATCH v3 RESENT 2/2] btrfs: qgroup: Don't copy extent buffer to do qgroup rescan Qu Wenruo
2015-10-22 8:16 ` Filipe Manana
2015-10-22 8:45 ` Qu Wenruo
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