From d50147381aa0c9725d63a677c138c47f55d6d3bc Mon Sep 17 00:00:00 2001 From: Omar Sandoval Date: Tue, 22 May 2018 09:47:58 -0700 Subject: Btrfs: fix error handling in btrfs_truncate() Jun Wu at Facebook reported that an internal service was seeing a return value of 1 from ftruncate() on Btrfs in some cases. This is coming from the NEED_TRUNCATE_BLOCK return value from btrfs_truncate_inode_items(). btrfs_truncate() uses two variables for error handling, ret and err. When btrfs_truncate_inode_items() returns non-zero, we set err to the return value. However, NEED_TRUNCATE_BLOCK is not an error. Make sure we only set err if ret is an error (i.e., negative). To reproduce the issue: mount a filesystem with -o compress-force=zstd and the following program will encounter return value of 1 from ftruncate: int main(void) { char buf[256] = { 0 }; int ret; int fd; fd = open("test", O_CREAT | O_WRONLY | O_TRUNC, 0666); if (fd == -1) { perror("open"); return EXIT_FAILURE; } if (write(fd, buf, sizeof(buf)) != sizeof(buf)) { perror("write"); close(fd); return EXIT_FAILURE; } if (fsync(fd) == -1) { perror("fsync"); close(fd); return EXIT_FAILURE; } ret = ftruncate(fd, 128); if (ret) { printf("ftruncate() returned %d\n", ret); close(fd); return EXIT_FAILURE; } close(fd); return EXIT_SUCCESS; } Fixes: ddfae63cc8e0 ("btrfs: move btrfs_truncate_block out of trans handle") CC: stable@vger.kernel.org # 4.15+ Reported-by: Jun Wu Signed-off-by: Omar Sandoval Signed-off-by: David Sterba --- fs/btrfs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 8e604e7071f1..d82afca0c05f 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -9124,7 +9124,8 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback) BTRFS_EXTENT_DATA_KEY); trans->block_rsv = &fs_info->trans_block_rsv; if (ret != -ENOSPC && ret != -EAGAIN) { - err = ret; + if (ret < 0) + err = ret; break; } -- cgit v1.2.3