[v2,6/9] btrfs: qgroup: Return actually freed bytes for qgroup release or free data
diff mbox

Message ID 20170313075216.5125-7-quwenruo@cn.fujitsu.com
State New
Headers show

Commit Message

Qu Wenruo March 13, 2017, 7:52 a.m. UTC
btrfs_qgroup_release/free_data() only returns 0 or minus error
number(ENOMEM is the only possible error).

This is normally good enough, but sometimes we need the accurate byte
number it freed/released.

Change it to return actually released/freed bytenr number instead of 0
for success.
And slightly modify related extent_changeset structure, since in btrfs
one none-hole data extent won't be larger than 128M, so "unsigned int"
is large enough for the use case.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
 fs/btrfs/extent-tree.c | 2 +-
 fs/btrfs/extent_io.h   | 2 +-
 fs/btrfs/qgroup.c      | 1 +
 3 files changed, 3 insertions(+), 2 deletions(-)

Comments

David Sterba March 30, 2017, 1:08 p.m. UTC | #1
On Mon, Mar 13, 2017 at 03:52:13PM +0800, Qu Wenruo wrote:
> btrfs_qgroup_release/free_data() only returns 0 or minus error
> number(ENOMEM is the only possible error).

btrfs_qgroup_release_data -> __btrfs_qgroup_release_data
will not allocate the ulist anymore, and there are no errors propagated
from clear_record_extent_bits (just 0), but there are still some
unhandled cases. So here a negative value should be expected anyway.

> This is normally good enough, but sometimes we need the accurate byte
> number it freed/released.
> 
> Change it to return actually released/freed bytenr number instead of 0
> for success.
> And slightly modify related extent_changeset structure, since in btrfs
> one none-hole data extent won't be larger than 128M, so "unsigned int"
> is large enough for the use case.

> -	u64 bytes_changed;
> +	unsigned int bytes_changed;

> @@ -2875,6 +2875,7 @@ static int __btrfs_qgroup_release_data(struct inode *inode, u64 start, u64 len,
>  		btrfs_qgroup_free_refroot(BTRFS_I(inode)->root->fs_info,
>  				BTRFS_I(inode)->root->objectid,
>  				changeset.bytes_changed);
> +	ret = changeset.bytes_changed;

This relies on the 128M limit, which will fit to int when assigned. I'm
thinking about the signedness, it makes sense to use unsigned for
bytes_changed, but we also need the negative error returned. Probably
ok.

>  out:
>  	ulist_release(&changeset.range_changed);
>  	return ret;
--
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Patch
diff mbox

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index be5477676cc8..89d1bcba3f8c 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4288,7 +4288,7 @@  int btrfs_check_data_free_space(struct inode *inode, u64 start, u64 len)
 
 	/* Use new btrfs_qgroup_reserve_data to reserve precious data space. */
 	ret = btrfs_qgroup_reserve_data(inode, start, len);
-	if (ret)
+	if (ret < 0)
 		btrfs_free_reserved_data_space_noquota(inode, start, len);
 	return ret;
 }
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 3e4fad4a909d..bdca004dc859 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -201,7 +201,7 @@  struct extent_buffer {
  */
 struct extent_changeset {
 	/* How many bytes are set/cleared in this operation */
-	u64 bytes_changed;
+	unsigned int bytes_changed;
 
 	/* Changed ranges */
 	struct ulist range_changed;
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 9535ea56b6f3..87aeefb34959 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -2875,6 +2875,7 @@  static int __btrfs_qgroup_release_data(struct inode *inode, u64 start, u64 len,
 		btrfs_qgroup_free_refroot(BTRFS_I(inode)->root->fs_info,
 				BTRFS_I(inode)->root->objectid,
 				changeset.bytes_changed);
+	ret = changeset.bytes_changed;
 out:
 	ulist_release(&changeset.range_changed);
 	return ret;