Btrfs: dummy extent buffers for tree mod log
The tree modification log needs two ways to create dummy extent buffers, once by allocating a fresh one (to rebuild an old root) and once by cloning an existing one (to make private rewind modifications) to it. Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
This commit is contained in:
parent
64947ec0d1
commit
815a51c74a
|
@ -3930,6 +3930,7 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
|
|||
eb->start = start;
|
||||
eb->len = len;
|
||||
eb->tree = tree;
|
||||
eb->bflags = 0;
|
||||
rwlock_init(&eb->lock);
|
||||
atomic_set(&eb->write_locks, 0);
|
||||
atomic_set(&eb->read_locks, 0);
|
||||
|
@ -3967,6 +3968,60 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
|
|||
return eb;
|
||||
}
|
||||
|
||||
struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
|
||||
{
|
||||
unsigned long i;
|
||||
struct page *p;
|
||||
struct extent_buffer *new;
|
||||
unsigned long num_pages = num_extent_pages(src->start, src->len);
|
||||
|
||||
new = __alloc_extent_buffer(NULL, src->start, src->len, GFP_ATOMIC);
|
||||
if (new == NULL)
|
||||
return NULL;
|
||||
|
||||
for (i = 0; i < num_pages; i++) {
|
||||
p = alloc_page(GFP_ATOMIC);
|
||||
BUG_ON(!p);
|
||||
attach_extent_buffer_page(new, p);
|
||||
WARN_ON(PageDirty(p));
|
||||
SetPageUptodate(p);
|
||||
new->pages[i] = p;
|
||||
}
|
||||
|
||||
copy_extent_buffer(new, src, 0, 0, src->len);
|
||||
set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags);
|
||||
set_bit(EXTENT_BUFFER_DUMMY, &new->bflags);
|
||||
|
||||
return new;
|
||||
}
|
||||
|
||||
struct extent_buffer *alloc_dummy_extent_buffer(u64 start, unsigned long len)
|
||||
{
|
||||
struct extent_buffer *eb;
|
||||
unsigned long num_pages = num_extent_pages(0, len);
|
||||
unsigned long i;
|
||||
|
||||
eb = __alloc_extent_buffer(NULL, start, len, GFP_ATOMIC);
|
||||
if (!eb)
|
||||
return NULL;
|
||||
|
||||
for (i = 0; i < num_pages; i++) {
|
||||
eb->pages[i] = alloc_page(GFP_ATOMIC);
|
||||
if (!eb->pages[i])
|
||||
goto err;
|
||||
}
|
||||
set_extent_buffer_uptodate(eb);
|
||||
btrfs_set_header_nritems(eb, 0);
|
||||
set_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
|
||||
|
||||
return eb;
|
||||
err:
|
||||
for (i--; i > 0; i--)
|
||||
__free_page(eb->pages[i]);
|
||||
__free_extent_buffer(eb);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
static int extent_buffer_under_io(struct extent_buffer *eb)
|
||||
{
|
||||
return (atomic_read(&eb->io_pages) ||
|
||||
|
@ -3982,6 +4037,7 @@ static void btrfs_release_extent_buffer_page(struct extent_buffer *eb,
|
|||
{
|
||||
unsigned long index;
|
||||
struct page *page;
|
||||
int mapped = !test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
|
||||
|
||||
BUG_ON(extent_buffer_under_io(eb));
|
||||
|
||||
|
@ -3992,7 +4048,7 @@ static void btrfs_release_extent_buffer_page(struct extent_buffer *eb,
|
|||
do {
|
||||
index--;
|
||||
page = extent_buffer_page(eb, index);
|
||||
if (page) {
|
||||
if (page && mapped) {
|
||||
spin_lock(&page->mapping->private_lock);
|
||||
/*
|
||||
* We do this since we'll remove the pages after we've
|
||||
|
@ -4017,6 +4073,8 @@ static void btrfs_release_extent_buffer_page(struct extent_buffer *eb,
|
|||
}
|
||||
spin_unlock(&page->mapping->private_lock);
|
||||
|
||||
}
|
||||
if (page) {
|
||||
/* One for when we alloced the page */
|
||||
page_cache_release(page);
|
||||
}
|
||||
|
@ -4235,14 +4293,18 @@ static void release_extent_buffer(struct extent_buffer *eb, gfp_t mask)
|
|||
{
|
||||
WARN_ON(atomic_read(&eb->refs) == 0);
|
||||
if (atomic_dec_and_test(&eb->refs)) {
|
||||
struct extent_io_tree *tree = eb->tree;
|
||||
if (test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags)) {
|
||||
spin_unlock(&eb->refs_lock);
|
||||
} else {
|
||||
struct extent_io_tree *tree = eb->tree;
|
||||
|
||||
spin_unlock(&eb->refs_lock);
|
||||
spin_unlock(&eb->refs_lock);
|
||||
|
||||
spin_lock(&tree->buffer_lock);
|
||||
radix_tree_delete(&tree->buffer,
|
||||
eb->start >> PAGE_CACHE_SHIFT);
|
||||
spin_unlock(&tree->buffer_lock);
|
||||
spin_lock(&tree->buffer_lock);
|
||||
radix_tree_delete(&tree->buffer,
|
||||
eb->start >> PAGE_CACHE_SHIFT);
|
||||
spin_unlock(&tree->buffer_lock);
|
||||
}
|
||||
|
||||
/* Should be safe to release our pages at this point */
|
||||
btrfs_release_extent_buffer_page(eb, 0);
|
||||
|
@ -4259,6 +4321,10 @@ void free_extent_buffer(struct extent_buffer *eb)
|
|||
return;
|
||||
|
||||
spin_lock(&eb->refs_lock);
|
||||
if (atomic_read(&eb->refs) == 2 &&
|
||||
test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))
|
||||
atomic_dec(&eb->refs);
|
||||
|
||||
if (atomic_read(&eb->refs) == 2 &&
|
||||
test_bit(EXTENT_BUFFER_STALE, &eb->bflags) &&
|
||||
!extent_buffer_under_io(eb) &&
|
||||
|
|
|
@ -39,6 +39,7 @@
|
|||
#define EXTENT_BUFFER_STALE 6
|
||||
#define EXTENT_BUFFER_WRITEBACK 7
|
||||
#define EXTENT_BUFFER_IOERR 8
|
||||
#define EXTENT_BUFFER_DUMMY 9
|
||||
|
||||
/* these are flags for extent_clear_unlock_delalloc */
|
||||
#define EXTENT_CLEAR_UNLOCK_PAGE 0x1
|
||||
|
@ -265,6 +266,8 @@ void set_page_extent_mapped(struct page *page);
|
|||
|
||||
struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
|
||||
u64 start, unsigned long len);
|
||||
struct extent_buffer *alloc_dummy_extent_buffer(u64 start, unsigned long len);
|
||||
struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src);
|
||||
struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
|
||||
u64 start, unsigned long len);
|
||||
void free_extent_buffer(struct extent_buffer *eb);
|
||||
|
|
Loading…
Reference in a new issue