Btrfs: deal with the case that we run out of space in the cache
Currently we don't handle running out of space in the cache, so to fix this we
keep track of how far in the cache we are. Then we only dirty the pages if we
successfully modify all of them, otherwise if we have an error or run out of
space we can just drop them and not worry about the vm writing them out.
Thanks,
Tested-by Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de>
Signed-off-by: Josef Bacik <josef@redhat.com>
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index f561c95..a3f420d 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -508,6 +508,7 @@
struct inode *inode;
struct rb_node *node;
struct list_head *pos, *n;
+ struct page **pages;
struct page *page;
struct extent_state *cached_state = NULL;
struct btrfs_free_cluster *cluster = NULL;
@@ -517,13 +518,13 @@
u64 start, end, len;
u64 bytes = 0;
u32 *crc, *checksums;
- pgoff_t index = 0, last_index = 0;
unsigned long first_page_offset;
- int num_checksums;
+ int index = 0, num_pages = 0;
int entries = 0;
int bitmaps = 0;
int ret = 0;
bool next_page = false;
+ bool out_of_space = false;
root = root->fs_info->tree_root;
@@ -551,24 +552,31 @@
return 0;
}
- last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
+ num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
+ PAGE_CACHE_SHIFT;
filemap_write_and_wait(inode->i_mapping);
btrfs_wait_ordered_range(inode, inode->i_size &
~(root->sectorsize - 1), (u64)-1);
/* We need a checksum per page. */
- num_checksums = i_size_read(inode) / PAGE_CACHE_SIZE;
- crc = checksums = kzalloc(sizeof(u32) * num_checksums, GFP_NOFS);
+ crc = checksums = kzalloc(sizeof(u32) * num_pages, GFP_NOFS);
if (!crc) {
iput(inode);
return 0;
}
+ pages = kzalloc(sizeof(struct page *) * num_pages, GFP_NOFS);
+ if (!pages) {
+ kfree(crc);
+ iput(inode);
+ return 0;
+ }
+
/* Since the first page has all of our checksums and our generation we
* need to calculate the offset into the page that we can start writing
* our entries.
*/
- first_page_offset = (sizeof(u32) * num_checksums) + sizeof(u64);
+ first_page_offset = (sizeof(u32) * num_pages) + sizeof(u64);
/* Get the cluster for this block_group if it exists */
if (!list_empty(&block_group->cluster_list))
@@ -590,20 +598,18 @@
* after find_get_page at this point. Just putting this here so people
* know and don't freak out.
*/
- while (index <= last_index) {
+ while (index < num_pages) {
page = grab_cache_page(inode->i_mapping, index);
if (!page) {
- pgoff_t i = 0;
+ int i;
- while (i < index) {
- page = find_get_page(inode->i_mapping, i);
- unlock_page(page);
- page_cache_release(page);
- page_cache_release(page);
- i++;
+ for (i = 0; i < num_pages; i++) {
+ unlock_page(pages[i]);
+ page_cache_release(pages[i]);
}
goto out_free;
}
+ pages[index] = page;
index++;
}
@@ -631,7 +637,12 @@
offset = start_offset;
}
- page = find_get_page(inode->i_mapping, index);
+ if (index >= num_pages) {
+ out_of_space = true;
+ break;
+ }
+
+ page = pages[index];
addr = kmap(page);
entry = addr + start_offset;
@@ -708,23 +719,6 @@
bytes += PAGE_CACHE_SIZE;
- ClearPageChecked(page);
- set_page_extent_mapped(page);
- SetPageUptodate(page);
- set_page_dirty(page);
-
- /*
- * We need to release our reference we got for grab_cache_page,
- * except for the first page which will hold our checksums, we
- * do that below.
- */
- if (index != 0) {
- unlock_page(page);
- page_cache_release(page);
- }
-
- page_cache_release(page);
-
index++;
} while (node || next_page);
@@ -734,6 +728,10 @@
struct btrfs_free_space *entry =
list_entry(pos, struct btrfs_free_space, list);
+ if (index >= num_pages) {
+ out_of_space = true;
+ break;
+ }
page = find_get_page(inode->i_mapping, index);
addr = kmap(page);
@@ -745,64 +743,58 @@
crc++;
bytes += PAGE_CACHE_SIZE;
- ClearPageChecked(page);
- set_page_extent_mapped(page);
- SetPageUptodate(page);
- set_page_dirty(page);
- unlock_page(page);
- page_cache_release(page);
- page_cache_release(page);
list_del_init(&entry->list);
index++;
}
+ if (out_of_space) {
+ btrfs_drop_pages(pages, num_pages);
+ unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
+ i_size_read(inode) - 1, &cached_state,
+ GFP_NOFS);
+ ret = 0;
+ goto out_free;
+ }
+
/* Zero out the rest of the pages just to make sure */
- while (index <= last_index) {
+ while (index < num_pages) {
void *addr;
- page = find_get_page(inode->i_mapping, index);
-
+ page = pages[index];
addr = kmap(page);
memset(addr, 0, PAGE_CACHE_SIZE);
kunmap(page);
- ClearPageChecked(page);
- set_page_extent_mapped(page);
- SetPageUptodate(page);
- set_page_dirty(page);
- unlock_page(page);
- page_cache_release(page);
- page_cache_release(page);
bytes += PAGE_CACHE_SIZE;
index++;
}
- btrfs_set_extent_delalloc(inode, 0, bytes - 1, &cached_state);
-
/* Write the checksums and trans id to the first page */
{
void *addr;
u64 *gen;
- page = find_get_page(inode->i_mapping, 0);
+ page = pages[0];
addr = kmap(page);
- memcpy(addr, checksums, sizeof(u32) * num_checksums);
- gen = addr + (sizeof(u32) * num_checksums);
+ memcpy(addr, checksums, sizeof(u32) * num_pages);
+ gen = addr + (sizeof(u32) * num_pages);
*gen = trans->transid;
kunmap(page);
- ClearPageChecked(page);
- set_page_extent_mapped(page);
- SetPageUptodate(page);
- set_page_dirty(page);
- unlock_page(page);
- page_cache_release(page);
- page_cache_release(page);
}
- BTRFS_I(inode)->generation = trans->transid;
+ ret = btrfs_dirty_pages(root, inode, pages, num_pages, 0,
+ bytes, &cached_state);
+ btrfs_drop_pages(pages, num_pages);
unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
i_size_read(inode) - 1, &cached_state, GFP_NOFS);
+ if (ret) {
+ ret = 0;
+ goto out_free;
+ }
+
+ BTRFS_I(inode)->generation = trans->transid;
+
filemap_write_and_wait(inode->i_mapping);
key.objectid = BTRFS_FREE_SPACE_OBJECTID;
@@ -853,6 +845,7 @@
BTRFS_I(inode)->generation = 0;
}
kfree(checksums);
+ kfree(pages);
btrfs_update_inode(trans, root, inode);
iput(inode);
return ret;