Btrfs: Avoid memcpy where possible in extent_buffers
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 30fbbd7..aed0861 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -483,15 +483,50 @@
#define BTRFS_SETGET_HEADER_FUNCS(name, type, member, bits) \
static inline u##bits btrfs_##name(struct extent_buffer *eb) \
{ \
- __le##bits res; \
- read_eb_member(eb, NULL, type, member, &res); \
- return le##bits##_to_cpu(res); \
+ int err; \
+ char *map_token; \
+ char *kaddr; \
+ unsigned long map_start; \
+ unsigned long map_len; \
+ unsigned long offset = offsetof(type, member); \
+ err = map_extent_buffer(eb, offset, \
+ sizeof(((type *)0)->member), \
+ &map_token, &kaddr, \
+ &map_start, &map_len, KM_USER0); \
+ if (!err) { \
+ __le##bits *tmp = (__le##bits *)(kaddr + offset - \
+ map_start); \
+ u##bits res = le##bits##_to_cpu(*tmp); \
+ unmap_extent_buffer(eb, map_token, KM_USER0); \
+ return res; \
+ } else { \
+ __le##bits res; \
+ read_eb_member(eb, NULL, type, member, &res); \
+ return le##bits##_to_cpu(res); \
+ } \
} \
static inline void btrfs_set_##name(struct extent_buffer *eb, \
u##bits val) \
{ \
- val = cpu_to_le##bits(val); \
- write_eb_member(eb, NULL, type, member, &val); \
+ int err; \
+ char *map_token; \
+ char *kaddr; \
+ unsigned long map_start; \
+ unsigned long map_len; \
+ unsigned long offset = offsetof(type, member); \
+ err = map_extent_buffer(eb, offset, \
+ sizeof(((type *)0)->member), \
+ &map_token, &kaddr, \
+ &map_start, &map_len, KM_USER0); \
+ if (!err) { \
+ __le##bits *tmp = (__le##bits *)(kaddr + offset - \
+ map_start); \
+ *tmp = cpu_to_le##bits(val); \
+ unmap_extent_buffer(eb, map_token, KM_USER0); \
+ } else { \
+ val = cpu_to_le##bits(val); \
+ write_eb_member(eb, NULL, type, member, &val); \
+ } \
}
#define BTRFS_SETGET_STACK_FUNCS(name, type, member, bits) \
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 0c1f90c..8242933 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -609,20 +609,20 @@
int btrfs_buffer_uptodate(struct extent_buffer *buf)
{
- struct inode *btree_inode = buf->pages[0]->mapping->host;
+ struct inode *btree_inode = buf->first_page->mapping->host;
return extent_buffer_uptodate(&BTRFS_I(btree_inode)->extent_tree, buf);
}
int btrfs_set_buffer_uptodate(struct extent_buffer *buf)
{
- struct inode *btree_inode = buf->pages[0]->mapping->host;
+ struct inode *btree_inode = buf->first_page->mapping->host;
return set_extent_buffer_uptodate(&BTRFS_I(btree_inode)->extent_tree,
buf);
}
void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
{
- struct btrfs_root *root = BTRFS_I(buf->pages[0]->mapping->host)->root;
+ struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
u64 transid = btrfs_header_generation(buf);
struct inode *btree_inode = root->fs_info->btree_inode;
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 8bef309..d2c733c 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -18,6 +18,11 @@
static struct kmem_cache *extent_map_cache;
static struct kmem_cache *extent_state_cache;
+static struct kmem_cache *extent_buffer_cache;
+static LIST_HEAD(extent_buffers);
+static spinlock_t extent_buffers_lock;
+static int nr_extent_buffers;
+#define MAX_EXTENT_BUFFER_CACHE 128
struct tree_entry {
u64 start;
@@ -29,21 +34,33 @@
void __init extent_map_init(void)
{
extent_map_cache = btrfs_cache_create("extent_map",
- sizeof(struct extent_map),
- SLAB_DESTROY_BY_RCU,
+ sizeof(struct extent_map), 0,
NULL);
extent_state_cache = btrfs_cache_create("extent_state",
- sizeof(struct extent_state),
- SLAB_DESTROY_BY_RCU,
+ sizeof(struct extent_state), 0,
NULL);
+ extent_buffer_cache = btrfs_cache_create("extent_buffers",
+ sizeof(struct extent_buffer), 0,
+ NULL);
+ spin_lock_init(&extent_buffers_lock);
}
void __exit extent_map_exit(void)
{
+ struct extent_buffer *eb;
+
+ while (!list_empty(&extent_buffers)) {
+ eb = list_entry(extent_buffers.next,
+ struct extent_buffer, list);
+ list_del(&eb->list);
+ kmem_cache_free(extent_buffer_cache, eb);
+ }
if (extent_map_cache)
kmem_cache_destroy(extent_map_cache);
if (extent_state_cache)
kmem_cache_destroy(extent_state_cache);
+ if (extent_buffer_cache)
+ kmem_cache_destroy(extent_buffer_cache);
}
void extent_map_tree_init(struct extent_map_tree *tree,
@@ -1858,6 +1875,48 @@
return (em->block_start + start - em->start) >> inode->i_blkbits;
}
+static struct extent_buffer *__alloc_extent_buffer(gfp_t mask)
+{
+ struct extent_buffer *eb = NULL;
+ spin_lock(&extent_buffers_lock);
+ if (!list_empty(&extent_buffers)) {
+ eb = list_entry(extent_buffers.next, struct extent_buffer,
+ list);
+ list_del(&eb->list);
+ WARN_ON(nr_extent_buffers == 0);
+ nr_extent_buffers--;
+ }
+ spin_unlock(&extent_buffers_lock);
+ if (eb) {
+ memset(eb, 0, sizeof(*eb));
+ return eb;
+ }
+ return kmem_cache_zalloc(extent_buffer_cache, mask);
+}
+
+static void __free_extent_buffer(struct extent_buffer *eb)
+{
+ if (nr_extent_buffers >= MAX_EXTENT_BUFFER_CACHE) {
+ kmem_cache_free(extent_buffer_cache, eb);
+ } else {
+ spin_lock(&extent_buffers_lock);
+ list_add(&eb->list, &extent_buffers);
+ nr_extent_buffers++;
+ spin_unlock(&extent_buffers_lock);
+ }
+}
+
+static inline struct page *extent_buffer_page(struct extent_buffer *eb, int i)
+{
+ struct page *p;
+ if (i == 0)
+ return eb->first_page;
+ i += eb->start >> PAGE_CACHE_SHIFT;
+ p = find_get_page(eb->first_page->mapping, i);
+ page_cache_release(p);
+ return p;
+}
+
struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
u64 start, unsigned long len,
gfp_t mask)
@@ -1871,7 +1930,7 @@
struct address_space *mapping = tree->mapping;
int uptodate = 0;
- eb = kzalloc(EXTENT_BUFFER_SIZE(num_pages), mask);
+ eb = __alloc_extent_buffer(mask);
if (!eb || IS_ERR(eb))
return NULL;
@@ -1881,9 +1940,16 @@
for (i = 0; i < num_pages; i++, index++) {
p = find_or_create_page(mapping, index, mask | __GFP_HIGHMEM);
- if (!p)
+ if (!p) {
+ /* make sure the free only frees the pages we've
+ * grabbed a reference on
+ */
+ eb->len = i << PAGE_CACHE_SHIFT;
+ eb->start &= ~((u64)PAGE_CACHE_SIZE - 1);
goto fail;
- eb->pages[i] = p;
+ }
+ if (i == 0)
+ eb->first_page = p;
if (!PageUptodate(p))
uptodate = 0;
unlock_page(p);
@@ -1909,7 +1975,7 @@
struct page *p;
struct address_space *mapping = tree->mapping;
- eb = kzalloc(EXTENT_BUFFER_SIZE(num_pages), mask);
+ eb = __alloc_extent_buffer(mask);
if (!eb || IS_ERR(eb))
return NULL;
@@ -1919,9 +1985,16 @@
for (i = 0; i < num_pages; i++, index++) {
p = find_get_page(mapping, index);
- if (!p)
+ if (!p) {
+ /* make sure the free only frees the pages we've
+ * grabbed a reference on
+ */
+ eb->len = i << PAGE_CACHE_SHIFT;
+ eb->start &= ~((u64)PAGE_CACHE_SIZE - 1);
goto fail;
- eb->pages[i] = p;
+ }
+ if (i == 0)
+ eb->first_page = p;
}
return eb;
fail:
@@ -1944,11 +2017,12 @@
num_pages = ((eb->start + eb->len - 1) >> PAGE_CACHE_SHIFT) -
(eb->start >> PAGE_CACHE_SHIFT) + 1;
- for (i = 0; i < num_pages; i++) {
- if (eb->pages[i])
- page_cache_release(eb->pages[i]);
+ if (eb->first_page)
+ page_cache_release(eb->first_page);
+ for (i = 1; i < num_pages; i++) {
+ page_cache_release(extent_buffer_page(eb, i));
}
- kfree(eb);
+ __free_extent_buffer(eb);
}
EXPORT_SYMBOL(free_extent_buffer);
@@ -1968,7 +2042,7 @@
(eb->start >> PAGE_CACHE_SHIFT) + 1;
for (i = 0; i < num_pages; i++) {
- page = eb->pages[i];
+ page = extent_buffer_page(eb, i);
lock_page(page);
/*
* if we're on the last page or the first page and the
@@ -2021,7 +2095,7 @@
set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
GFP_NOFS);
for (i = 0; i < num_pages; i++) {
- page = eb->pages[i];
+ page = extent_buffer_page(eb, i);
if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
((i == num_pages - 1) &&
((eb->start + eb->len - 1) & (PAGE_CACHE_SIZE - 1)))) {
@@ -2064,7 +2138,7 @@
num_pages = ((eb->start + eb->len - 1) >> PAGE_CACHE_SHIFT) -
(eb->start >> PAGE_CACHE_SHIFT) + 1;
for (i = 0; i < num_pages; i++) {
- page = eb->pages[i];
+ page = extent_buffer_page(eb, i);
if (PageUptodate(page)) {
continue;
}
@@ -2090,7 +2164,7 @@
}
for (i = 0; i < num_pages; i++) {
- page = eb->pages[i];
+ page = extent_buffer_page(eb, i);
wait_on_page_locked(page);
if (!PageUptodate(page)) {
ret = -EIO;
@@ -2116,12 +2190,12 @@
WARN_ON(start > eb->len);
WARN_ON(start + len > eb->start + eb->len);
- page = eb->pages[i];
offset = start & ((unsigned long)PAGE_CACHE_SIZE - 1);
if (i == 0)
offset += start_offset;
while(len > 0) {
+ page = extent_buffer_page(eb, i);
WARN_ON(!PageUptodate(page));
cur = min(len, (PAGE_CACHE_SIZE - offset));
@@ -2134,7 +2208,6 @@
len -= cur;
offset = 0;
i++;
- page = eb->pages[i];
}
}
EXPORT_SYMBOL(read_extent_buffer);
@@ -2165,7 +2238,7 @@
}
// kaddr = kmap_atomic(eb->pages[i], km);
- kaddr = page_address(eb->pages[i]);
+ kaddr = page_address(extent_buffer_page(eb, i));
*token = kaddr;
*map = kaddr + offset;
*map_len = PAGE_CACHE_SIZE - offset;
@@ -2195,12 +2268,12 @@
WARN_ON(start > eb->len);
WARN_ON(start + len > eb->start + eb->len);
- page = eb->pages[i];
offset = start & ((unsigned long)PAGE_CACHE_SIZE - 1);
if (i == 0)
offset += start_offset;
while(len > 0) {
+ page = extent_buffer_page(eb, i);
WARN_ON(!PageUptodate(page));
cur = min(len, (PAGE_CACHE_SIZE - offset));
@@ -2216,7 +2289,6 @@
len -= cur;
offset = 0;
i++;
- page = eb->pages[i];
}
return ret;
}
@@ -2236,12 +2308,12 @@
WARN_ON(start > eb->len);
WARN_ON(start + len > eb->start + eb->len);
- page = eb->pages[i];
offset = start & ((unsigned long)PAGE_CACHE_SIZE - 1);
if (i == 0)
offset += start_offset;
while(len > 0) {
+ page = extent_buffer_page(eb, i);
WARN_ON(!PageUptodate(page));
cur = min(len, PAGE_CACHE_SIZE - offset);
@@ -2254,7 +2326,6 @@
len -= cur;
offset = 0;
i++;
- page = eb->pages[i];
}
}
EXPORT_SYMBOL(write_extent_buffer);
@@ -2272,12 +2343,12 @@
WARN_ON(start > eb->len);
WARN_ON(start + len > eb->start + eb->len);
- page = eb->pages[i];
offset = start & ((unsigned long)PAGE_CACHE_SIZE - 1);
if (i == 0)
offset += start_offset;
while(len > 0) {
+ page = extent_buffer_page(eb, i);
WARN_ON(!PageUptodate(page));
cur = min(len, PAGE_CACHE_SIZE - offset);
@@ -2289,7 +2360,6 @@
len -= cur;
offset = 0;
i++;
- page = eb->pages[i];
}
}
EXPORT_SYMBOL(memset_extent_buffer);
@@ -2313,7 +2383,7 @@
offset += start_offset;
while(len > 0) {
- page = dst->pages[i];
+ page = extent_buffer_page(dst, i);
WARN_ON(!PageUptodate(page));
cur = min(len, (unsigned long)(PAGE_CACHE_SIZE - offset));
@@ -2414,7 +2484,8 @@
cur = min(cur, (unsigned long)(PAGE_CACHE_SIZE -
dst_off_in_page));
- copy_pages(dst->pages[dst_i], dst->pages[src_i],
+ copy_pages(extent_buffer_page(dst, dst_i),
+ extent_buffer_page(dst, src_i),
dst_off_in_page, src_off_in_page, cur);
src_offset += cur;
@@ -2467,7 +2538,8 @@
cur = min(len, src_off_in_page + 1);
cur = min(cur, dst_off_in_page + 1);
// printk("move pages orig dst %lu src %lu len %lu, this %lu %lu %lu\n", dst_offset, src_offset, len, dst_off_in_page - cur + 1, src_off_in_page - cur + 1, cur);
- move_pages(dst->pages[dst_i], dst->pages[src_i],
+ move_pages(extent_buffer_page(dst, dst_i),
+ extent_buffer_page(dst, src_i),
dst_off_in_page - cur + 1,
src_off_in_page - cur + 1, cur);
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 8957890..3b3abf3 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -62,14 +62,13 @@
struct list_head list;
};
-#define EXTENT_BUFFER_SIZE(nr) (sizeof(struct extent_buffer) + \
- (nr - 1) * sizeof(struct page *))
struct extent_buffer {
u64 start;
unsigned long len;
atomic_t refs;
int flags;
- struct page *pages[];
+ struct list_head list;
+ struct page *first_page;
};
typedef struct extent_map *(get_extent_t)(struct inode *inode,