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Btrfs: Fix compressed writes on truncated pages

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The compression code was using isize to limit the amount of data it
sent through zlib.  But, it wasn't properly limiting the looping to
just the pages inside i_size.  The end result was trying to compress
too many pages, including those that had not been setup and properly locked
down.  This made the compression code oops while trying find_get_page on a
page that didn't exist.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2008-12-15 11:44:56 -05:00
parent 17d217fe97
commit 42dc7babdc
2 changed files with 6 additions and 4 deletions
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2
fs/btrfs/ctree.c
View File

@ -2887,8 +2887,8 @@ int btrfs_split_item(struct btrfs_trans_handle *trans,
path->keep_locks = 0;
BUG_ON(ret);
BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
leaf = path->nodes[0];
BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
split:
item = btrfs_item_nr(leaf, path->slots[0]);

8
fs/btrfs/inode.c
View File

@ -332,6 +332,7 @@ static noinline int compress_file_range(struct inode *inode,
u64 disk_num_bytes;
u64 blocksize = root->sectorsize;
u64 actual_end;
u64 isize = i_size_read(inode);
int ret = 0;
struct page **pages = NULL;
unsigned long nr_pages;
@ -345,12 +346,12 @@ static noinline int compress_file_range(struct inode *inode,
orig_start = start;
actual_end = min_t(u64, isize, end + 1);
again:
will_compress = 0;
nr_pages = (end >> PAGE_CACHE_SHIFT) - (start >> PAGE_CACHE_SHIFT) + 1;
nr_pages = min(nr_pages, (128 * 1024UL) / PAGE_CACHE_SIZE);
actual_end = min_t(u64, i_size_read(inode), end + 1);
total_compressed = actual_end - start;
/* we want to make sure that amount of ram required to uncompress
@ -488,7 +489,7 @@ again:
add_async_extent(async_cow, start, num_bytes,
total_compressed, pages, nr_pages_ret);
if (start + num_bytes < end) {
if (start + num_bytes < end && start + num_bytes < actual_end) {
start += num_bytes;
pages = NULL;
cond_resched();
@ -696,6 +697,7 @@ static noinline int cow_file_range(struct inode *inode,
u64 cur_alloc_size;
u64 blocksize = root->sectorsize;
u64 actual_end;
u64 isize = i_size_read(inode);
struct btrfs_key ins;
struct extent_map *em;
struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
@ -705,7 +707,7 @@ static noinline int cow_file_range(struct inode *inode,
BUG_ON(!trans);
btrfs_set_trans_block_group(trans, inode);
actual_end = min_t(u64, i_size_read(inode), end + 1);
actual_end = min_t(u64, isize, end + 1);
num_bytes = (end - start + blocksize) & ~(blocksize - 1);
num_bytes = max(blocksize, num_bytes);