Liu Bo
2013-Sep-16 08:18 UTC
[PATCH v2] Btrfs: export btrfs space shared info to userspace
Similar to ocfs2, btrfs also supports that extents can be shared by
different inodes, and there are some userspace tools requesting
for this kind of ''space shared infomation''.[1]
ocfs2 uses flag FIEMAP_EXTENT_SHARED, so does btrfs.
[1]:
http://thr3ads.net/ocfs2-devel/2010/09/489052-PATCH-3-3-shared-du-using-fiemap-to-figure-up-the-shared-extents-per-file-and-the-footprint-in
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
---
v2: use ''unsigned long'' instead of ''int''.
fs/btrfs/extent_io.c | 34 +++++++++++++++++++++++++++++++++-
1 files changed, 33 insertions(+), 1 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 09582b8..a097441 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -20,6 +20,7 @@
#include "check-integrity.h"
#include "locking.h"
#include "rcu-string.h"
+#include "backref.h"
static struct kmem_cache *extent_state_cache;
static struct kmem_cache *extent_buffer_cache;
@@ -4056,6 +4057,19 @@ static struct extent_map *get_extent_skip_holes(struct
inode *inode,
return NULL;
}
+static noinline int count_ext_ref(u64 inum, u64 offset, u64 root_id, void *ctx)
+{
+ unsigned long cnt = *((unsigned long *)ctx);
+
+ cnt++;
+ *((unsigned long *)ctx) = cnt;
+
+ /* Now we''re sure that the extent is shared. */
+ if (cnt > 1)
+ return 1;
+ return 0;
+}
+
int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
__u64 start, __u64 len, get_extent_t *get_extent)
{
@@ -4122,7 +4136,7 @@ int extent_fiemap(struct inode *inode, struct
fiemap_extent_info *fieinfo,
last = found_key.offset;
last_for_get_extent = last + 1;
}
- btrfs_free_path(path);
+ btrfs_release_path(path);
/*
* we might have some extents allocated but more delalloc past those
@@ -4192,7 +4206,24 @@ int extent_fiemap(struct inode *inode, struct
fiemap_extent_info *fieinfo,
flags |= (FIEMAP_EXTENT_DELALLOC |
FIEMAP_EXTENT_UNKNOWN);
} else {
+ unsigned long ref_cnt = 0;
+
disko = em->block_start + offset_in_extent;
+
+ /*
+ * As btrfs supports shared space, this information
+ * can be exported to userspace tools via
+ * flag FIEMAP_EXTENT_SHARED.
+ */
+ ret = iterate_inodes_from_logical(
+ em->block_start,
+ BTRFS_I(inode)->root->fs_info,
+ path, count_ext_ref, &ref_cnt);
+ if (ret < 0)
+ goto out_free;
+
+ if (ref_cnt > 1)
+ flags |= FIEMAP_EXTENT_SHARED;
}
if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
flags |= FIEMAP_EXTENT_ENCODED;
@@ -4226,6 +4257,7 @@ out_free:
out:
unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1,
&cached_state, GFP_NOFS);
+ btrfs_free_path(path);
return ret;
}
--
1.7.7
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David Sterba
2013-Sep-16 08:55 UTC
Re: [PATCH v2] Btrfs: export btrfs space shared info to userspace
On Mon, Sep 16, 2013 at 04:18:24PM +0800, Liu Bo wrote:> @@ -4122,7 +4136,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > last = found_key.offset; > last_for_get_extent = last + 1; > } > - btrfs_free_path(path); > + btrfs_release_path(path); > > /* > * we might have some extents allocated but more delalloc past those > @@ -4192,7 +4206,24 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > flags |= (FIEMAP_EXTENT_DELALLOC | > FIEMAP_EXTENT_UNKNOWN); > } else { > + unsigned long ref_cnt = 0; > + > disko = em->block_start + offset_in_extent; > + > + /* > + * As btrfs supports shared space, this information > + * can be exported to userspace tools via > + * flag FIEMAP_EXTENT_SHARED. > + */ > + ret = iterate_inodes_from_logical( > + em->block_start, > + BTRFS_I(inode)->root->fs_info, > + path, count_ext_ref, &ref_cnt); > + if (ret < 0) > + goto out_free; > + > + if (ref_cnt > 1) > + flags |= FIEMAP_EXTENT_SHARED; > } > if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) > flags |= FIEMAP_EXTENT_ENCODED; > @@ -4226,6 +4257,7 @@ out_free: > out: > unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1, > &cached_state, GFP_NOFS); > + btrfs_free_path(path);I think this free_path should go before unlock_extent_cached, it''s not needed for unlock_extent_cached itself and will delay unlocking the path unnecessarily (it''s set to leave_spinning = 1).> return ret; > }-- 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
Liu Bo
2013-Sep-16 09:28 UTC
Re: [PATCH v2] Btrfs: export btrfs space shared info to userspace
On Mon, Sep 16, 2013 at 10:55:17AM +0200, David Sterba wrote:> On Mon, Sep 16, 2013 at 04:18:24PM +0800, Liu Bo wrote: > > @@ -4122,7 +4136,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > > last = found_key.offset; > > last_for_get_extent = last + 1; > > } > > - btrfs_free_path(path); > > + btrfs_release_path(path); > > > > /* > > * we might have some extents allocated but more delalloc past those > > @@ -4192,7 +4206,24 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > > flags |= (FIEMAP_EXTENT_DELALLOC | > > FIEMAP_EXTENT_UNKNOWN); > > } else { > > + unsigned long ref_cnt = 0; > > + > > disko = em->block_start + offset_in_extent; > > + > > + /* > > + * As btrfs supports shared space, this information > > + * can be exported to userspace tools via > > + * flag FIEMAP_EXTENT_SHARED. > > + */ > > + ret = iterate_inodes_from_logical( > > + em->block_start, > > + BTRFS_I(inode)->root->fs_info, > > + path, count_ext_ref, &ref_cnt); > > + if (ret < 0) > > + goto out_free; > > + > > + if (ref_cnt > 1) > > + flags |= FIEMAP_EXTENT_SHARED; > > } > > if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) > > flags |= FIEMAP_EXTENT_ENCODED; > > @@ -4226,6 +4257,7 @@ out_free: > > out: > > unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1, > > &cached_state, GFP_NOFS); > > + btrfs_free_path(path); > > I think this free_path should go before unlock_extent_cached, it''s not > needed for unlock_extent_cached itself and will delay unlocking the > path unnecessarily (it''s set to leave_spinning = 1).Path has been released and unlocked inside iterate_inodes_from_logical() though. But yeah, path is unrelevant with unlock_extent_cached(), it can be done earlier. -liubo> > > return ret; > > }-- 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