Btrfs: Use a mutex in the extent buffer for tree block locking
This replaces the use of the page cache lock bit for locking, which wasn't
suitable for block size < page size and couldn't be used recursively.
The mutexes alone don't fix either problem, but they are the first step.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index ccd4932..c51cd11 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1451,7 +1451,7 @@
struct extent_buffer *buf;
buf = btrfs_find_tree_block(root, bytenr, num_bytes);
if (buf) {
- if (!btrfs_try_tree_lock(buf) &&
+ if (btrfs_try_tree_lock(buf) &&
btrfs_buffer_uptodate(buf, 0)) {
u64 transid =
root->fs_info->running_transaction->transid;
@@ -3345,11 +3345,6 @@
set_state_private(block_group_cache, found_key.objectid,
(unsigned long)cache);
- /* hack for now */
- if (cache->flags & BTRFS_BLOCK_GROUP_METADATA) {
- cache_block_group(root->fs_info->extent_root,
- cache);
- }
if (key.objectid >=
btrfs_super_total_bytes(&info->super_copy))
break;
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 32bb4ed..7380449 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2690,6 +2690,7 @@
eb = kmem_cache_zalloc(extent_buffer_cache, mask);
eb->start = start;
eb->len = len;
+ mutex_init(&eb->mutex);
spin_lock_irqsave(&leak_lock, flags);
list_add(&eb->leak_list, &buffers);
spin_unlock_irqrestore(&leak_lock, flags);
@@ -2837,6 +2838,7 @@
for (i = 0; i < num_pages; i++) {
page = extent_buffer_page(eb, i);
+ lock_page(page);
if (i == 0)
set_page_extent_head(page, eb->len);
else
@@ -2854,6 +2856,7 @@
end = start + PAGE_CACHE_SIZE - 1;
if (test_range_bit(tree, start, end,
EXTENT_DIRTY, 0)) {
+ unlock_page(page);
continue;
}
}
@@ -2865,6 +2868,7 @@
PAGECACHE_TAG_DIRTY);
}
read_unlock_irq(&page->mapping->tree_lock);
+ unlock_page(page);
}
return 0;
}
@@ -2893,12 +2897,17 @@
* on us if the page isn't already dirty.
*/
if (i == 0) {
+ lock_page(page);
set_page_extent_head(page, eb->len);
} else if (PagePrivate(page) &&
page->private != EXTENT_PAGE_PRIVATE) {
+ lock_page(page);
set_page_extent_mapped(page);
+ unlock_page(page);
}
__set_page_dirty_nobuffers(extent_buffer_page(eb, i));
+ if (i == 0)
+ unlock_page(page);
}
return set_extent_dirty(tree, eb->start,
eb->start + eb->len - 1, GFP_NOFS);
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index dd36761..6c03e6a 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -90,6 +90,7 @@
int flags;
struct list_head leak_list;
struct rb_node rb_node;
+ struct mutex mutex;
};
struct extent_map_tree;
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 058a506..01a9ac2 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -29,32 +29,31 @@
{
int i;
- if (!TestSetPageLocked(eb->first_page))
+ if (mutex_trylock(&eb->mutex))
return 0;
for (i = 0; i < 512; i++) {
cpu_relax();
- if (!TestSetPageLocked(eb->first_page))
+ if (mutex_trylock(&eb->mutex))
return 0;
}
cpu_relax();
- lock_page(eb->first_page);
+ mutex_lock(&eb->mutex);
return 0;
}
int btrfs_try_tree_lock(struct extent_buffer *eb)
{
- return TestSetPageLocked(eb->first_page);
+ return mutex_trylock(&eb->mutex);
}
int btrfs_tree_unlock(struct extent_buffer *eb)
{
- WARN_ON(!PageLocked(eb->first_page));
- unlock_page(eb->first_page);
+ mutex_unlock(&eb->mutex);
return 0;
}
int btrfs_tree_locked(struct extent_buffer *eb)
{
- return PageLocked(eb->first_page);
+ return mutex_is_locked(&eb->mutex);
}