btrfs: extended inode ref iteration
The iterate_irefs in backref.c is used to build path components from inode
refs. This patch adds code to iterate extended refs as well.
I had modify the callback function signature to abstract out some of the
differences between ref structures. iref_to_path() also needed similar
changes.
Signed-off-by: Mark Fasheh <mfasheh@suse.de>
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index dc96312..f318793 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1177,26 +1177,12 @@
return ret;
}
-/*
- * this iterates to turn a btrfs_inode_ref into a full filesystem path. elements
- * of the path are separated by '/' and the path is guaranteed to be
- * 0-terminated. the path is only given within the current file system.
- * Therefore, it never starts with a '/'. the caller is responsible to provide
- * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
- * the start point of the resulting string is returned. this pointer is within
- * dest, normally.
- * in case the path buffer would overflow, the pointer is decremented further
- * as if output was written to the buffer, though no more output is actually
- * generated. that way, the caller can determine how much space would be
- * required for the path to fit into the buffer. in that case, the returned
- * value will be smaller than dest. callers must check this!
- */
-char *btrfs_iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
- struct btrfs_inode_ref *iref,
+static char *ref_to_path(struct btrfs_root *fs_root,
+ struct btrfs_path *path,
+ u32 name_len, unsigned long name_off,
struct extent_buffer *eb_in, u64 parent,
char *dest, u32 size)
{
- u32 len;
int slot;
u64 next_inum;
int ret;
@@ -1204,17 +1190,17 @@
struct extent_buffer *eb = eb_in;
struct btrfs_key found_key;
int leave_spinning = path->leave_spinning;
+ struct btrfs_inode_ref *iref;
if (bytes_left >= 0)
dest[bytes_left] = '\0';
path->leave_spinning = 1;
while (1) {
- len = btrfs_inode_ref_name_len(eb, iref);
- bytes_left -= len;
+ bytes_left -= name_len;
if (bytes_left >= 0)
read_extent_buffer(eb, dest + bytes_left,
- (unsigned long)(iref + 1), len);
+ name_off, name_len);
if (eb != eb_in) {
btrfs_tree_read_unlock_blocking(eb);
free_extent_buffer(eb);
@@ -1224,6 +1210,7 @@
ret = -ENOENT;
if (ret)
break;
+
next_inum = found_key.offset;
/* regular exit ahead */
@@ -1239,8 +1226,11 @@
btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
}
btrfs_release_path(path);
-
iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
+
+ name_len = btrfs_inode_ref_name_len(eb, iref);
+ name_off = (unsigned long)(iref + 1);
+
parent = next_inum;
--bytes_left;
if (bytes_left >= 0)
@@ -1257,6 +1247,32 @@
}
/*
+ * this iterates to turn a btrfs_inode_ref into a full filesystem path. elements
+ * of the path are separated by '/' and the path is guaranteed to be
+ * 0-terminated. the path is only given within the current file system.
+ * Therefore, it never starts with a '/'. the caller is responsible to provide
+ * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
+ * the start point of the resulting string is returned. this pointer is within
+ * dest, normally.
+ * in case the path buffer would overflow, the pointer is decremented further
+ * as if output was written to the buffer, though no more output is actually
+ * generated. that way, the caller can determine how much space would be
+ * required for the path to fit into the buffer. in that case, the returned
+ * value will be smaller than dest. callers must check this!
+ */
+char *btrfs_iref_to_path(struct btrfs_root *fs_root,
+ struct btrfs_path *path,
+ struct btrfs_inode_ref *iref,
+ struct extent_buffer *eb_in, u64 parent,
+ char *dest, u32 size)
+{
+ return ref_to_path(fs_root, path,
+ btrfs_inode_ref_name_len(eb_in, iref),
+ (unsigned long)(iref + 1),
+ eb_in, parent, dest, size);
+}
+
+/*
* this makes the path point to (logical EXTENT_ITEM *)
* returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
* tree blocks and <0 on error.
@@ -1529,9 +1545,12 @@
return ret;
}
-static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
- struct btrfs_path *path,
- iterate_irefs_t *iterate, void *ctx)
+typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
+ struct extent_buffer *eb, void *ctx);
+
+static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
+ struct btrfs_path *path,
+ iterate_irefs_t *iterate, void *ctx)
{
int ret = 0;
int slot;
@@ -1548,7 +1567,7 @@
while (!ret) {
path->leave_spinning = 1;
ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
- &found_key);
+ &found_key);
if (ret < 0)
break;
if (ret) {
@@ -1576,7 +1595,8 @@
"tree %llu\n", cur,
(unsigned long long)found_key.objectid,
(unsigned long long)fs_root->objectid);
- ret = iterate(parent, iref, eb, ctx);
+ ret = iterate(parent, name_len,
+ (unsigned long)(iref + 1), eb, ctx);
if (ret)
break;
len = sizeof(*iref) + name_len;
@@ -1591,12 +1611,98 @@
return ret;
}
+static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
+ struct btrfs_path *path,
+ iterate_irefs_t *iterate, void *ctx)
+{
+ int ret;
+ int slot;
+ u64 offset = 0;
+ u64 parent;
+ int found = 0;
+ struct extent_buffer *eb;
+ struct btrfs_inode_extref *extref;
+ struct extent_buffer *leaf;
+ u32 item_size;
+ u32 cur_offset;
+ unsigned long ptr;
+
+ while (1) {
+ ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
+ &offset);
+ if (ret < 0)
+ break;
+ if (ret) {
+ ret = found ? 0 : -ENOENT;
+ break;
+ }
+ ++found;
+
+ slot = path->slots[0];
+ eb = path->nodes[0];
+ /* make sure we can use eb after releasing the path */
+ atomic_inc(&eb->refs);
+
+ btrfs_tree_read_lock(eb);
+ btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
+ btrfs_release_path(path);
+
+ leaf = path->nodes[0];
+ item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+ ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
+ cur_offset = 0;
+
+ while (cur_offset < item_size) {
+ u32 name_len;
+
+ extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
+ parent = btrfs_inode_extref_parent(eb, extref);
+ name_len = btrfs_inode_extref_name_len(eb, extref);
+ ret = iterate(parent, name_len,
+ (unsigned long)&extref->name, eb, ctx);
+ if (ret)
+ break;
+
+ cur_offset += btrfs_inode_extref_name_len(leaf, extref);
+ cur_offset += sizeof(*extref);
+ }
+ btrfs_tree_read_unlock_blocking(eb);
+ free_extent_buffer(eb);
+
+ offset++;
+ }
+
+ btrfs_release_path(path);
+
+ return ret;
+}
+
+static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
+ struct btrfs_path *path, iterate_irefs_t *iterate,
+ void *ctx)
+{
+ int ret;
+ int found_refs = 0;
+
+ ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
+ if (!ret)
+ ++found_refs;
+ else if (ret != -ENOENT)
+ return ret;
+
+ ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
+ if (ret == -ENOENT && found_refs)
+ return 0;
+
+ return ret;
+}
+
/*
* returns 0 if the path could be dumped (probably truncated)
* returns <0 in case of an error
*/
-static int inode_to_path(u64 inum, struct btrfs_inode_ref *iref,
- struct extent_buffer *eb, void *ctx)
+static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
+ struct extent_buffer *eb, void *ctx)
{
struct inode_fs_paths *ipath = ctx;
char *fspath;
@@ -1609,20 +1715,17 @@
ipath->fspath->bytes_left - s_ptr : 0;
fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
- fspath = btrfs_iref_to_path(ipath->fs_root, ipath->btrfs_path, iref, eb,
- inum, fspath_min, bytes_left);
+ fspath = ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
+ name_off, eb, inum, fspath_min,
+ bytes_left);
if (IS_ERR(fspath))
return PTR_ERR(fspath);
if (fspath > fspath_min) {
- pr_debug("path resolved: %s\n", fspath);
ipath->fspath->val[i] = (u64)(unsigned long)fspath;
++ipath->fspath->elem_cnt;
ipath->fspath->bytes_left = fspath - fspath_min;
} else {
- pr_debug("missed path, not enough space. missing bytes: %lu, "
- "constructed so far: %s\n",
- (unsigned long)(fspath_min - fspath), fspath_min);
++ipath->fspath->elem_missed;
ipath->fspath->bytes_missing += fspath_min - fspath;
ipath->fspath->bytes_left = 0;
@@ -1644,7 +1747,7 @@
int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
{
return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
- inode_to_path, ipath);
+ inode_to_path, ipath);
}
struct btrfs_data_container *init_data_container(u32 total_bytes)