From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:22111 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751062Ab3IPHk0 (ORCPT ); Mon, 16 Sep 2013 03:40:26 -0400 From: Liu Bo To: linux-btrfs@vger.kernel.org Cc: dsterba@suse.cz, jeff.liu@oracle.com Subject: [PATCH] Btrfs: export btrfs space shared info to userspace Date: Mon, 16 Sep 2013 15:40:12 +0800 Message-Id: <1379317212-20246-1-git-send-email-bo.li.liu@oracle.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: 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 --- RFC->PATCH: use type 'unsigned long' instead of 'int', as David suggested. 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..efd91d7 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) +{ + int cnt = *((int *)ctx); + + cnt++; + *((int *)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