| Message ID | 1401999351-8281-1-git-send-email-jbacik@fb.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Thu, Jun 05, 2014 at 04:15:51PM -0400, Josef Bacik wrote: > We have been iterating all references for each extent we have in a file when we > do fiemap to see if it is shared. This is fine when you have a few clones or a > few snapshots, but when you have 5k snapshots suddenly fiemap just sits there > and stares at you. So add btrfs_check_shared which will use the backref walking > code but will short circuit as soon as it finds a root or inode that doesn't > match the one we currently have. This makes fiemap on my testbox go from > looking at me blankly for a day to spitting out actual output in a reasonable > amount of time. Thanks, > > Signed-off-by: Josef Bacik <jbacik@fb.com> > --- > fs/btrfs/backref.c | 109 +++++++++++++++++++++++++++++++++++++++++++++------ > fs/btrfs/backref.h | 3 ++ > fs/btrfs/extent_io.c | 44 ++++++++------------- > 3 files changed, 118 insertions(+), 38 deletions(-) > > diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c > index 84d0912..baacc41 100644 > --- a/fs/btrfs/backref.c > +++ b/fs/btrfs/backref.c > @@ -25,6 +25,9 @@ > #include "delayed-ref.h" > #include "locking.h" > > +/* Just an arbitrary number so we can be sure this happened */ > +#define BACKREF_FOUND_SHARED 6 > + > struct extent_inode_elem { > u64 inum; > u64 offset; > @@ -378,7 +381,8 @@ out: > static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info, > struct btrfs_path *path, u64 time_seq, > struct list_head *head, > - const u64 *extent_item_pos, u64 total_refs) > + const u64 *extent_item_pos, u64 total_refs, > + u64 root_objectid) > { > int err; > int ret = 0; > @@ -403,6 +407,10 @@ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info, > continue; > if (ref->count == 0) > continue; > + if (root_objectid && ref->root_id != root_objectid) { > + ret = BACKREF_FOUND_SHARED; > + goto out; > + } > err = __resolve_indirect_ref(fs_info, path, time_seq, ref, > parents, extent_item_pos, > total_refs); > @@ -562,7 +570,8 @@ static void __merge_refs(struct list_head *head, int mode) > * smaller or equal that seq to the list > */ > static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq, > - struct list_head *prefs, u64 *total_refs) > + struct list_head *prefs, u64 *total_refs, > + u64 inum) > { > struct btrfs_delayed_extent_op *extent_op = head->extent_op; > struct rb_node *n = &head->node.rb_node; > @@ -626,6 +635,16 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq, > key.objectid = ref->objectid; > key.type = BTRFS_EXTENT_DATA_KEY; > key.offset = ref->offset; > + > + /* > + * Found a inum that doesn't match our known inum, we > + * know it's shared. > + */ > + if (inum && ref->objectid != inum) { > + ret = BACKREF_FOUND_SHARED; > + break; > + } > + These can be put ahead of assigning key's value. > ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0, > node->bytenr, > node->ref_mod * sgn, GFP_ATOMIC); > @@ -660,7 +679,7 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq, > static int __add_inline_refs(struct btrfs_fs_info *fs_info, > struct btrfs_path *path, u64 bytenr, > int *info_level, struct list_head *prefs, > - u64 *total_refs) > + u64 *total_refs, u64 inum) > { > int ret = 0; > int slot; > @@ -745,6 +764,12 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info, > dref); > key.type = BTRFS_EXTENT_DATA_KEY; > key.offset = btrfs_extent_data_ref_offset(leaf, dref); > + > + if (inum && key.objectid != inum) { > + ret = BACKREF_FOUND_SHARED; > + break; > + } > + > root = btrfs_extent_data_ref_root(leaf, dref); > ret = __add_prelim_ref(prefs, root, &key, 0, 0, > bytenr, count, GFP_NOFS); > @@ -766,7 +791,7 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info, > */ > static int __add_keyed_refs(struct btrfs_fs_info *fs_info, > struct btrfs_path *path, u64 bytenr, > - int info_level, struct list_head *prefs) > + int info_level, struct list_head *prefs, u64 inum) > { > struct btrfs_root *extent_root = fs_info->extent_root; > int ret; > @@ -828,6 +853,12 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info, > dref); > key.type = BTRFS_EXTENT_DATA_KEY; > key.offset = btrfs_extent_data_ref_offset(leaf, dref); > + > + if (inum && key.objectid != inum) { > + ret = BACKREF_FOUND_SHARED; > + break; > + } > + > root = btrfs_extent_data_ref_root(leaf, dref); > ret = __add_prelim_ref(prefs, root, &key, 0, 0, > bytenr, count, GFP_NOFS); > @@ -855,7 +886,8 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info, > static int find_parent_nodes(struct btrfs_trans_handle *trans, > struct btrfs_fs_info *fs_info, u64 bytenr, > u64 time_seq, struct ulist *refs, > - struct ulist *roots, const u64 *extent_item_pos) > + struct ulist *roots, const u64 *extent_item_pos, > + u64 root_objectid, u64 inum) > { > struct btrfs_key key; > struct btrfs_path *path; > @@ -930,7 +962,8 @@ again: > } > spin_unlock(&delayed_refs->lock); > ret = __add_delayed_refs(head, time_seq, > - &prefs_delayed, &total_refs); > + &prefs_delayed, &total_refs, > + inum); > mutex_unlock(&head->mutex); > if (ret) > goto out; > @@ -952,11 +985,11 @@ again: > key.type == BTRFS_METADATA_ITEM_KEY)) { > ret = __add_inline_refs(fs_info, path, bytenr, > &info_level, &prefs, > - &total_refs); > + &total_refs, inum); > if (ret) > goto out; > ret = __add_keyed_refs(fs_info, path, bytenr, > - info_level, &prefs); > + info_level, &prefs, inum); > if (ret) > goto out; > } > @@ -972,7 +1005,8 @@ again: > __merge_refs(&prefs, 1); > > ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs, > - extent_item_pos, total_refs); > + extent_item_pos, total_refs, > + root_objectid); > if (ret) > goto out; > > @@ -982,6 +1016,11 @@ again: > ref = list_first_entry(&prefs, struct __prelim_ref, list); > WARN_ON(ref->count < 0); > if (roots && ref->count && ref->root_id && ref->parent == 0) { > + if (root_objectid && ref->root_id != root_objectid) { > + ret = BACKREF_FOUND_SHARED; > + goto out; > + } > + > /* no parent == root of tree */ > ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS); > if (ret < 0) > @@ -1085,7 +1124,7 @@ static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans, > return -ENOMEM; > > ret = find_parent_nodes(trans, fs_info, bytenr, > - time_seq, *leafs, NULL, extent_item_pos); > + time_seq, *leafs, NULL, extent_item_pos, 0, 0); > if (ret < 0 && ret != -ENOENT) { > free_leaf_list(*leafs); > return ret; > @@ -1128,7 +1167,7 @@ static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans, > ULIST_ITER_INIT(&uiter); > while (1) { > ret = find_parent_nodes(trans, fs_info, bytenr, > - time_seq, tmp, *roots, NULL); > + time_seq, tmp, *roots, NULL, 0, 0); > if (ret < 0 && ret != -ENOENT) { > ulist_free(tmp); > ulist_free(*roots); > @@ -1159,6 +1198,54 @@ int btrfs_find_all_roots(struct btrfs_trans_handle *trans, > return ret; > } > > +int btrfs_check_shared(struct btrfs_trans_handle *trans, > + struct btrfs_fs_info *fs_info, u64 root_objectid, > + u64 inum, u64 bytenr) > +{ Hmm...a less generic name may be better. Others look good. thanks, -liubo > + struct ulist *tmp = NULL; > + struct ulist *roots = NULL; > + struct ulist_iterator uiter; > + struct ulist_node *node; > + struct seq_list elem = {}; > + int ret = 0; > + > + tmp = ulist_alloc(GFP_NOFS); > + roots = ulist_alloc(GFP_NOFS); > + if (!tmp || !roots) { > + ulist_free(tmp); > + ulist_free(roots); > + return -ENOMEM; > + } > + > + if (trans) > + btrfs_get_tree_mod_seq(fs_info, &elem); > + else > + down_read(&fs_info->commit_root_sem); > + ULIST_ITER_INIT(&uiter); > + while (1) { > + ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp, > + roots, NULL, root_objectid, inum); > + if (ret == BACKREF_FOUND_SHARED) { > + ret = 1; > + break; > + } > + if (ret < 0 && ret != -ENOENT) > + break; > + node = ulist_next(tmp, &uiter); > + if (!node) > + break; > + bytenr = node->val; > + cond_resched(); > + } > + if (trans) > + btrfs_put_tree_mod_seq(fs_info, &elem); > + else > + up_read(&fs_info->commit_root_sem); > + ulist_free(tmp); > + ulist_free(roots); > + return ret; > +} > + > /* > * this makes the path point to (inum INODE_ITEM ioff) > */ > diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h > index 94e9442..71fef59 100644 > --- a/fs/btrfs/backref.h > +++ b/fs/btrfs/backref.h > @@ -71,6 +71,9 @@ int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid, > u64 start_off, struct btrfs_path *path, > struct btrfs_inode_extref **ret_extref, > u64 *found_off); > +int btrfs_check_shared(struct btrfs_trans_handle *trans, > + struct btrfs_fs_info *fs_info, u64 root_objectid, > + u64 inum, u64 bytenr); > > int __init btrfs_prelim_ref_init(void); > void btrfs_prelim_ref_exit(void); > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index 8285ed0..d5fb685 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -4113,19 +4113,6 @@ 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) > { > @@ -4142,6 +4129,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > struct extent_map *em = NULL; > struct extent_state *cached_state = NULL; > struct btrfs_path *path; > + struct btrfs_root *root = BTRFS_I(inode)->root; > int end = 0; > u64 em_start = 0; > u64 em_len = 0; > @@ -4155,15 +4143,15 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > return -ENOMEM; > path->leave_spinning = 1; > > - start = ALIGN(start, BTRFS_I(inode)->root->sectorsize); > - len = ALIGN(len, BTRFS_I(inode)->root->sectorsize); > + start = ALIGN(start, root->sectorsize); > + len = ALIGN(len, root->sectorsize); > > /* > * lookup the last file extent. We're not using i_size here > * because there might be preallocation past i_size > */ > - ret = btrfs_lookup_file_extent(NULL, BTRFS_I(inode)->root, > - path, btrfs_ino(inode), -1, 0); > + ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(inode), -1, > + 0); > if (ret < 0) { > btrfs_free_path(path); > return ret; > @@ -4256,25 +4244,27 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > } else if (em->block_start == EXTENT_MAP_DELALLOC) { > flags |= (FIEMAP_EXTENT_DELALLOC | > FIEMAP_EXTENT_UNKNOWN); > - } else { > - unsigned long ref_cnt = 0; > + } else if (fieinfo->fi_extents_max) { > + u64 bytenr = em->block_start - > + (em->start - em->orig_start); > > 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. > + * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 > + * then we're just getting a count and we can skip the > + * lookup stuff. > */ > - ret = iterate_inodes_from_logical( > - em->block_start, > - BTRFS_I(inode)->root->fs_info, > - path, count_ext_ref, &ref_cnt); > - if (ret < 0 && ret != -ENOENT) > + ret = btrfs_check_shared(NULL, root->fs_info, > + root->objectid, > + btrfs_ino(inode), bytenr); > + if (ret < 0) > goto out_free; > - > - if (ref_cnt > 1) > + if (ret) > flags |= FIEMAP_EXTENT_SHARED; > + ret = 0; > } > if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) > flags |= FIEMAP_EXTENT_ENCODED; > -- > 1.8.3.1 > > -- > 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 -- 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
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index 84d0912..baacc41 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -25,6 +25,9 @@ #include "delayed-ref.h" #include "locking.h" +/* Just an arbitrary number so we can be sure this happened */ +#define BACKREF_FOUND_SHARED 6 + struct extent_inode_elem { u64 inum; u64 offset; @@ -378,7 +381,8 @@ out: static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info, struct btrfs_path *path, u64 time_seq, struct list_head *head, - const u64 *extent_item_pos, u64 total_refs) + const u64 *extent_item_pos, u64 total_refs, + u64 root_objectid) { int err; int ret = 0; @@ -403,6 +407,10 @@ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info, continue; if (ref->count == 0) continue; + if (root_objectid && ref->root_id != root_objectid) { + ret = BACKREF_FOUND_SHARED; + goto out; + } err = __resolve_indirect_ref(fs_info, path, time_seq, ref, parents, extent_item_pos, total_refs); @@ -562,7 +570,8 @@ static void __merge_refs(struct list_head *head, int mode) * smaller or equal that seq to the list */ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq, - struct list_head *prefs, u64 *total_refs) + struct list_head *prefs, u64 *total_refs, + u64 inum) { struct btrfs_delayed_extent_op *extent_op = head->extent_op; struct rb_node *n = &head->node.rb_node; @@ -626,6 +635,16 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq, key.objectid = ref->objectid; key.type = BTRFS_EXTENT_DATA_KEY; key.offset = ref->offset; + + /* + * Found a inum that doesn't match our known inum, we + * know it's shared. + */ + if (inum && ref->objectid != inum) { + ret = BACKREF_FOUND_SHARED; + break; + } + ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0, node->bytenr, node->ref_mod * sgn, GFP_ATOMIC); @@ -660,7 +679,7 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq, static int __add_inline_refs(struct btrfs_fs_info *fs_info, struct btrfs_path *path, u64 bytenr, int *info_level, struct list_head *prefs, - u64 *total_refs) + u64 *total_refs, u64 inum) { int ret = 0; int slot; @@ -745,6 +764,12 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info, dref); key.type = BTRFS_EXTENT_DATA_KEY; key.offset = btrfs_extent_data_ref_offset(leaf, dref); + + if (inum && key.objectid != inum) { + ret = BACKREF_FOUND_SHARED; + break; + } + root = btrfs_extent_data_ref_root(leaf, dref); ret = __add_prelim_ref(prefs, root, &key, 0, 0, bytenr, count, GFP_NOFS); @@ -766,7 +791,7 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info, */ static int __add_keyed_refs(struct btrfs_fs_info *fs_info, struct btrfs_path *path, u64 bytenr, - int info_level, struct list_head *prefs) + int info_level, struct list_head *prefs, u64 inum) { struct btrfs_root *extent_root = fs_info->extent_root; int ret; @@ -828,6 +853,12 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info, dref); key.type = BTRFS_EXTENT_DATA_KEY; key.offset = btrfs_extent_data_ref_offset(leaf, dref); + + if (inum && key.objectid != inum) { + ret = BACKREF_FOUND_SHARED; + break; + } + root = btrfs_extent_data_ref_root(leaf, dref); ret = __add_prelim_ref(prefs, root, &key, 0, 0, bytenr, count, GFP_NOFS); @@ -855,7 +886,8 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info, static int find_parent_nodes(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info, u64 bytenr, u64 time_seq, struct ulist *refs, - struct ulist *roots, const u64 *extent_item_pos) + struct ulist *roots, const u64 *extent_item_pos, + u64 root_objectid, u64 inum) { struct btrfs_key key; struct btrfs_path *path; @@ -930,7 +962,8 @@ again: } spin_unlock(&delayed_refs->lock); ret = __add_delayed_refs(head, time_seq, - &prefs_delayed, &total_refs); + &prefs_delayed, &total_refs, + inum); mutex_unlock(&head->mutex); if (ret) goto out; @@ -952,11 +985,11 @@ again: key.type == BTRFS_METADATA_ITEM_KEY)) { ret = __add_inline_refs(fs_info, path, bytenr, &info_level, &prefs, - &total_refs); + &total_refs, inum); if (ret) goto out; ret = __add_keyed_refs(fs_info, path, bytenr, - info_level, &prefs); + info_level, &prefs, inum); if (ret) goto out; } @@ -972,7 +1005,8 @@ again: __merge_refs(&prefs, 1); ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs, - extent_item_pos, total_refs); + extent_item_pos, total_refs, + root_objectid); if (ret) goto out; @@ -982,6 +1016,11 @@ again: ref = list_first_entry(&prefs, struct __prelim_ref, list); WARN_ON(ref->count < 0); if (roots && ref->count && ref->root_id && ref->parent == 0) { + if (root_objectid && ref->root_id != root_objectid) { + ret = BACKREF_FOUND_SHARED; + goto out; + } + /* no parent == root of tree */ ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS); if (ret < 0) @@ -1085,7 +1124,7 @@ static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans, return -ENOMEM; ret = find_parent_nodes(trans, fs_info, bytenr, - time_seq, *leafs, NULL, extent_item_pos); + time_seq, *leafs, NULL, extent_item_pos, 0, 0); if (ret < 0 && ret != -ENOENT) { free_leaf_list(*leafs); return ret; @@ -1128,7 +1167,7 @@ static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans, ULIST_ITER_INIT(&uiter); while (1) { ret = find_parent_nodes(trans, fs_info, bytenr, - time_seq, tmp, *roots, NULL); + time_seq, tmp, *roots, NULL, 0, 0); if (ret < 0 && ret != -ENOENT) { ulist_free(tmp); ulist_free(*roots); @@ -1159,6 +1198,54 @@ int btrfs_find_all_roots(struct btrfs_trans_handle *trans, return ret; } +int btrfs_check_shared(struct btrfs_trans_handle *trans, + struct btrfs_fs_info *fs_info, u64 root_objectid, + u64 inum, u64 bytenr) +{ + struct ulist *tmp = NULL; + struct ulist *roots = NULL; + struct ulist_iterator uiter; + struct ulist_node *node; + struct seq_list elem = {}; + int ret = 0; + + tmp = ulist_alloc(GFP_NOFS); + roots = ulist_alloc(GFP_NOFS); + if (!tmp || !roots) { + ulist_free(tmp); + ulist_free(roots); + return -ENOMEM; + } + + if (trans) + btrfs_get_tree_mod_seq(fs_info, &elem); + else + down_read(&fs_info->commit_root_sem); + ULIST_ITER_INIT(&uiter); + while (1) { + ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp, + roots, NULL, root_objectid, inum); + if (ret == BACKREF_FOUND_SHARED) { + ret = 1; + break; + } + if (ret < 0 && ret != -ENOENT) + break; + node = ulist_next(tmp, &uiter); + if (!node) + break; + bytenr = node->val; + cond_resched(); + } + if (trans) + btrfs_put_tree_mod_seq(fs_info, &elem); + else + up_read(&fs_info->commit_root_sem); + ulist_free(tmp); + ulist_free(roots); + return ret; +} + /* * this makes the path point to (inum INODE_ITEM ioff) */ diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h index 94e9442..71fef59 100644 --- a/fs/btrfs/backref.h +++ b/fs/btrfs/backref.h @@ -71,6 +71,9 @@ int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid, u64 start_off, struct btrfs_path *path, struct btrfs_inode_extref **ret_extref, u64 *found_off); +int btrfs_check_shared(struct btrfs_trans_handle *trans, + struct btrfs_fs_info *fs_info, u64 root_objectid, + u64 inum, u64 bytenr); int __init btrfs_prelim_ref_init(void); void btrfs_prelim_ref_exit(void); diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 8285ed0..d5fb685 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -4113,19 +4113,6 @@ 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) { @@ -4142,6 +4129,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, struct extent_map *em = NULL; struct extent_state *cached_state = NULL; struct btrfs_path *path; + struct btrfs_root *root = BTRFS_I(inode)->root; int end = 0; u64 em_start = 0; u64 em_len = 0; @@ -4155,15 +4143,15 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, return -ENOMEM; path->leave_spinning = 1; - start = ALIGN(start, BTRFS_I(inode)->root->sectorsize); - len = ALIGN(len, BTRFS_I(inode)->root->sectorsize); + start = ALIGN(start, root->sectorsize); + len = ALIGN(len, root->sectorsize); /* * lookup the last file extent. We're not using i_size here * because there might be preallocation past i_size */ - ret = btrfs_lookup_file_extent(NULL, BTRFS_I(inode)->root, - path, btrfs_ino(inode), -1, 0); + ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(inode), -1, + 0); if (ret < 0) { btrfs_free_path(path); return ret; @@ -4256,25 +4244,27 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, } else if (em->block_start == EXTENT_MAP_DELALLOC) { flags |= (FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN); - } else { - unsigned long ref_cnt = 0; + } else if (fieinfo->fi_extents_max) { + u64 bytenr = em->block_start - + (em->start - em->orig_start); 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. + * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 + * then we're just getting a count and we can skip the + * lookup stuff. */ - ret = iterate_inodes_from_logical( - em->block_start, - BTRFS_I(inode)->root->fs_info, - path, count_ext_ref, &ref_cnt); - if (ret < 0 && ret != -ENOENT) + ret = btrfs_check_shared(NULL, root->fs_info, + root->objectid, + btrfs_ino(inode), bytenr); + if (ret < 0) goto out_free; - - if (ref_cnt > 1) + if (ret) flags |= FIEMAP_EXTENT_SHARED; + ret = 0; } if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) flags |= FIEMAP_EXTENT_ENCODED;
We have been iterating all references for each extent we have in a file when we do fiemap to see if it is shared. This is fine when you have a few clones or a few snapshots, but when you have 5k snapshots suddenly fiemap just sits there and stares at you. So add btrfs_check_shared which will use the backref walking code but will short circuit as soon as it finds a root or inode that doesn't match the one we currently have. This makes fiemap on my testbox go from looking at me blankly for a day to spitting out actual output in a reasonable amount of time. Thanks, Signed-off-by: Josef Bacik <jbacik@fb.com> --- fs/btrfs/backref.c | 109 +++++++++++++++++++++++++++++++++++++++++++++------ fs/btrfs/backref.h | 3 ++ fs/btrfs/extent_io.c | 44 ++++++++------------- 3 files changed, 118 insertions(+), 38 deletions(-)