f2fs: do not preallocate blocks which has wrong buffer
Sheng Yong reports needless preallocation if write(small_buffer, large_size)
is called.
In that case, f2fs preallocates large_size, but vfs returns early due to
small_buffer size. Let's detect it before preallocation phase in f2fs.
Reported-by: Sheng Yong <shengyong1@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index e455221..9c0f469 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -20,6 +20,7 @@
#include <linux/uaccess.h>
#include <linux/mount.h>
#include <linux/pagevec.h>
+#include <linux/uio.h>
#include <linux/uuid.h>
#include <linux/file.h>
@@ -2258,8 +2259,12 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
inode_lock(inode);
ret = generic_write_checks(iocb, from);
if (ret > 0) {
- int err = f2fs_preallocate_blocks(iocb, from);
+ int err;
+ if (iov_iter_fault_in_readable(from, iov_iter_count(from)))
+ set_inode_flag(inode, FI_NO_PREALLOC);
+
+ err = f2fs_preallocate_blocks(iocb, from);
if (err) {
inode_unlock(inode);
return err;
@@ -2267,6 +2272,7 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
blk_start_plug(&plug);
ret = __generic_file_write_iter(iocb, from);
blk_finish_plug(&plug);
+ clear_inode_flag(inode, FI_NO_PREALLOC);
}
inode_unlock(inode);