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Btrfs: Properly find the root for snapshotted blocks during chunk relocation 

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2008-05-08 13:26:18 -04:00
parent a061fc8da7
commit bf4ef67924
3 changed files with 156 additions and 12 deletions
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2
fs/btrfs/ctree.h
View File

@ -1459,6 +1459,8 @@ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
*item);
int btrfs_find_last_root(struct btrfs_root *root, u64 objectid, struct
btrfs_root_item *item, struct btrfs_key *key);
int btrfs_search_root(struct btrfs_root *root, u64 search_start,
u64 *found_objectid);
int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid,
struct btrfs_root *latest_root);
/* dir-item.c */

120
fs/btrfs/extent-tree.c
View File

@ -2421,6 +2421,85 @@ truncate_racing:
goto out_unlock;
}
/*
* The back references tell us which tree holds a ref on a block,
* but it is possible for the tree root field in the reference to
* reflect the original root before a snapshot was made. In this
* case we should search through all the children of a given root
* to find potential holders of references on a block.
*
* Instead, we do something a little less fancy and just search
* all the roots for a given key/block combination.
*/
static int find_root_for_ref(struct btrfs_root *root,
struct btrfs_path *path,
struct btrfs_key *key0,
int level,
int file_key,
struct btrfs_root **found_root,
u64 bytenr)
{
struct btrfs_key root_location;
struct btrfs_root *cur_root = *found_root;
struct btrfs_file_extent_item *file_extent;
u64 root_search_start = BTRFS_FS_TREE_OBJECTID;
u64 found_bytenr;
int ret;
int i;
root_location.offset = (u64)-1;
root_location.type = BTRFS_ROOT_ITEM_KEY;
path->lowest_level = level;
path->reada = 0;
while(1) {
ret = btrfs_search_slot(NULL, cur_root, key0, path, 0, 0);
found_bytenr = 0;
if (ret == 0 && file_key) {
struct extent_buffer *leaf = path->nodes[0];
file_extent = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
if (btrfs_file_extent_type(leaf, file_extent) ==
BTRFS_FILE_EXTENT_REG) {
found_bytenr =
btrfs_file_extent_disk_bytenr(leaf,
file_extent);
}
} else if (ret == 0) {
if (path->nodes[level])
found_bytenr = path->nodes[level]->start;
}
for (i = level; i < BTRFS_MAX_LEVEL; i++) {
if (!path->nodes[i])
break;
free_extent_buffer(path->nodes[i]);
path->nodes[i] = NULL;
}
btrfs_release_path(cur_root, path);
if (found_bytenr == bytenr) {
*found_root = cur_root;
ret = 0;
goto out;
}
ret = btrfs_search_root(root->fs_info->tree_root,
root_search_start, &root_search_start);
if (ret)
break;
root_location.objectid = root_search_start;
cur_root = btrfs_read_fs_root_no_name(root->fs_info,
&root_location);
if (!cur_root) {
ret = 1;
break;
}
}
out:
path->lowest_level = 0;
return ret;
}
/*
* note, this releases the path
*/
@ -2430,13 +2509,15 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
{
struct inode *inode;
struct btrfs_root *found_root;
struct btrfs_key *root_location;
struct btrfs_key root_location;
struct btrfs_key found_key;
struct btrfs_extent_ref *ref;
u64 ref_root;
u64 ref_gen;
u64 ref_objectid;
u64 ref_offset;
int ret;
int level;
ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
struct btrfs_extent_ref);
@ -2446,20 +2527,30 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
ref_offset = btrfs_ref_offset(path->nodes[0], ref);
btrfs_release_path(extent_root, path);
root_location = kmalloc(sizeof(*root_location), GFP_NOFS);
root_location->objectid = ref_root;
root_location.objectid = ref_root;
if (ref_gen == 0)
root_location->offset = 0;
root_location.offset = 0;
else
root_location->offset = (u64)-1;
root_location->type = BTRFS_ROOT_ITEM_KEY;
root_location.offset = (u64)-1;
root_location.type = BTRFS_ROOT_ITEM_KEY;
found_root = btrfs_read_fs_root_no_name(extent_root->fs_info,
root_location);
&root_location);
BUG_ON(!found_root);
kfree(root_location);
if (ref_objectid >= BTRFS_FIRST_FREE_OBJECTID) {
found_key.objectid = ref_objectid;
found_key.type = BTRFS_EXTENT_DATA_KEY;
found_key.offset = ref_offset;
level = 0;
ret = find_root_for_ref(extent_root, path, &found_key,
level, 1, &found_root,
extent_key->objectid);
if (ret)
goto out;
mutex_unlock(&extent_root->fs_info->fs_mutex);
inode = btrfs_iget_locked(extent_root->fs_info->sb,
ref_objectid, found_root);
@ -2485,12 +2576,9 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
mutex_lock(&extent_root->fs_info->fs_mutex);
} else {
struct btrfs_trans_handle *trans;
struct btrfs_key found_key;
struct extent_buffer *eb;
int level;
int i;
trans = btrfs_start_transaction(found_root, 1);
eb = read_tree_block(found_root, extent_key->objectid,
extent_key->offset);
level = btrfs_header_level(eb);
@ -2502,6 +2590,15 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
free_extent_buffer(eb);
ret = find_root_for_ref(extent_root, path, &found_key,
level, 0, &found_root,
extent_key->objectid);
if (ret)
goto out;
trans = btrfs_start_transaction(found_root, 1);
path->lowest_level = level;
path->reada = 2;
ret = btrfs_search_slot(trans, found_root, &found_key, path,
@ -2578,6 +2675,7 @@ static int noinline relocate_one_extent(struct btrfs_root *extent_root,
}
if (ret < 0)
goto out;
leaf = path->nodes[0];
}
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);

46
fs/btrfs/root-tree.c
View File

@ -21,6 +21,51 @@
#include "disk-io.h"
#include "print-tree.h"
/*
* returns 0 on finding something, 1 if no more roots are there
* and < 0 on error
*/
int btrfs_search_root(struct btrfs_root *root, u64 search_start,
u64 *found_objectid)
{
struct btrfs_path *path;
struct btrfs_key search_key;
int ret;
root = root->fs_info->tree_root;
search_key.objectid = search_start;
search_key.type = (u8)-1;
search_key.offset = (u64)-1;
path = btrfs_alloc_path();
BUG_ON(!path);
again:
ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
if (ret < 0)
goto out;
if (ret == 0) {
ret = 1;
goto out;
}
if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
ret = btrfs_next_leaf(root, path);
if (ret)
goto out;
}
btrfs_item_key_to_cpu(path->nodes[0], &search_key, path->slots[0]);
if (search_key.type != BTRFS_ROOT_ITEM_KEY) {
search_key.offset++;
btrfs_release_path(root, path);
goto again;
}
ret = 0;
*found_objectid = search_key.objectid;
out:
btrfs_free_path(path);
return ret;
}
int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
struct btrfs_root_item *item, struct btrfs_key *key)
{
@ -55,7 +100,6 @@ int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
memcpy(key, &found_key, sizeof(found_key));
ret = 0;
out:
btrfs_release_path(root, path);
btrfs_free_path(path);
return ret;
}