f2fs: fix avoid race between truncate and background GC
Thread A Background GC
- f2fs_setattr isize to 0
- truncate_setsize
- gc_data_segment
- f2fs_get_read_data_page page #0
- set_page_dirty
- set_cold_data
- f2fs_truncate
- f2fs_setattr isize to 4k
- read 4k <--- hit data in cached page #0
Above race condition can cause read out invalid data in a truncated
page, fix it by i_gc_rwsem[WRITE] lock.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 4cb0202..8c4694b 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -796,22 +796,26 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
}
if (attr->ia_valid & ATTR_SIZE) {
- if (attr->ia_size <= i_size_read(inode)) {
- down_write(&F2FS_I(inode)->i_mmap_sem);
- truncate_setsize(inode, attr->ia_size);
- err = f2fs_truncate(inode);
- up_write(&F2FS_I(inode)->i_mmap_sem);
- if (err)
- return err;
- } else {
- /*
- * do not trim all blocks after i_size if target size is
- * larger than i_size.
- */
- down_write(&F2FS_I(inode)->i_mmap_sem);
- truncate_setsize(inode, attr->ia_size);
- up_write(&F2FS_I(inode)->i_mmap_sem);
+ bool to_smaller = (attr->ia_size <= i_size_read(inode));
+ down_write(&F2FS_I(inode)->i_mmap_sem);
+ down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+
+ truncate_setsize(inode, attr->ia_size);
+
+ if (to_smaller)
+ err = f2fs_truncate(inode);
+ /*
+ * do not trim all blocks after i_size if target size is
+ * larger than i_size.
+ */
+ up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+ up_write(&F2FS_I(inode)->i_mmap_sem);
+
+ if (err)
+ return err;
+
+ if (!to_smaller) {
/* should convert inline inode here */
if (!f2fs_may_inline_data(inode)) {
err = f2fs_convert_inline_inode(inode);
@@ -958,13 +962,18 @@ static int punch_hole(struct inode *inode, loff_t offset, loff_t len)
blk_start = (loff_t)pg_start << PAGE_SHIFT;
blk_end = (loff_t)pg_end << PAGE_SHIFT;
+
down_write(&F2FS_I(inode)->i_mmap_sem);
+ down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+
truncate_inode_pages_range(mapping, blk_start,
blk_end - 1);
f2fs_lock_op(sbi);
ret = f2fs_truncate_hole(inode, pg_start, pg_end);
f2fs_unlock_op(sbi);
+
+ up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
up_write(&F2FS_I(inode)->i_mmap_sem);
}
}