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Btrfs: fix return value for __tree_mod_log_oldest_root

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In __tree_mod_log_oldest_root() we must return the found operation even if
it's not a ROOT_REPLACE operation. Otherwise, the caller assumes that there
are no operations to be rewinded and returns immediately.

The code in the caller is modified to improve readability.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
This commit is contained in:
Jan Schmidt 2012-06-05 16:41:24 +02:00
parent 8ba97a15e7
commit a95236d99f
1 changed files with 20 additions and 13 deletions
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33
fs/btrfs/ctree.c
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@ -1023,6 +1023,10 @@ __tree_mod_log_oldest_root(struct btrfs_fs_info *fs_info,
looped = 1;
}
/* if there's no old root to return, return what we found instead */
if (!found)
found = tm;
return found;
}
@ -1155,18 +1159,24 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
{
struct tree_mod_elem *tm;
struct extent_buffer *eb;
struct tree_mod_root *old_root;
struct tree_mod_root *old_root = NULL;
u64 old_generation;
u64 logical;
eb = btrfs_read_lock_root_node(root);
tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
if (!tm)
return root->node;
old_root = &tm->old_root;
old_generation = tm->generation;
if (tm->op == MOD_LOG_ROOT_REPLACE) {
old_root = &tm->old_root;
old_generation = tm->generation;
logical = old_root->logical;
} else {
logical = root->node->start;
}
tm = tree_mod_log_search(root->fs_info, old_root->logical, time_seq);
tm = tree_mod_log_search(root->fs_info, logical, time_seq);
/*
* there was an item in the log when __tree_mod_log_oldest_root
* returned. this one must not go away, because the time_seq passed to
@ -1174,26 +1184,23 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
*/
BUG_ON(!tm);
if (old_root->logical == root->node->start) {
/* there are logged operations for the current root */
eb = btrfs_clone_extent_buffer(root->node);
} else {
/* there's a root replace operation for the current root */
if (old_root)
eb = alloc_dummy_extent_buffer(tm->index << PAGE_CACHE_SHIFT,
root->nodesize);
}
else
eb = btrfs_clone_extent_buffer(root->node);
btrfs_tree_read_unlock(root->node);
free_extent_buffer(root->node);
if (!eb)
return NULL;
btrfs_tree_read_lock(eb);
if (old_root->logical != root->node->start) {
if (old_root) {
btrfs_set_header_bytenr(eb, eb->start);
btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
btrfs_set_header_owner(eb, root->root_key.objectid);
btrfs_set_header_level(eb, old_root->level);
btrfs_set_header_generation(eb, old_generation);
}
btrfs_set_header_level(eb, old_root->level);
btrfs_set_header_generation(eb, old_generation);
__tree_mod_log_rewind(eb, time_seq, tm);
extent_buffer_get(eb);