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authorJosef Bacik <jbacik@fb.com>2014-09-10 16:20:45 -0400
committerChris Mason <clm@fb.com>2014-09-17 13:38:24 -0700
commitdc046b10c8b7d4f40befe457acb82340bf8b0699 (patch)
tree2659e92649b19df4cd54a65eabd34f961f8d57f8 /fs/btrfs/backref.c
parent78a017a2c92df9b571db0a55a016280f9019c65e (diff)
downloadop-kernel-dev-dc046b10c8b7d4f40befe457acb82340bf8b0699.zip
op-kernel-dev-dc046b10c8b7d4f40befe457acb82340bf8b0699.tar.gz
Btrfs: make fiemap not blow when you have lots of snapshots
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> Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs/btrfs/backref.c')
-rw-r--r--fs/btrfs/backref.c109
1 files changed, 98 insertions, 11 deletions
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 4de9792..6829dc5 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;
@@ -377,7 +380,8 @@ 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;
@@ -402,6 +406,10 @@ 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);
@@ -561,7 +569,8 @@ 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;
@@ -625,6 +634,16 @@ 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);
@@ -659,7 +678,7 @@ 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;
@@ -744,6 +763,12 @@ 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);
@@ -765,7 +790,7 @@ 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;
@@ -827,6 +852,12 @@ 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);
@@ -854,7 +885,8 @@ 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;
@@ -929,7 +961,8 @@ 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;
@@ -951,11 +984,11 @@ 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;
}
@@ -971,7 +1004,8 @@ 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;
@@ -981,6 +1015,11 @@ 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)
@@ -1087,7 +1126,7 @@ 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;
@@ -1130,7 +1169,7 @@ 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);
@@ -1161,6 +1200,54 @@ 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)
*/
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