From b6a535faed06c2bdfaf55b00025dfdcb1eadf980 Mon Sep 17 00:00:00 2001 From: Howard McLauchlan Date: Fri, 2 Feb 2018 11:09:01 -0800 Subject: [PATCH] btrfs: print error if primary super block write fails Presently, failing a primary super block write but succeeding in at least one super block write in general will appear to users as if nothing important went wrong. However, upon unmounting and re-mounting, the file system will be in a rolled back state. This was discovered with a BCC program that uses bpf_override_return() to fail super block writes. This patch outputs an error clarifying that the primary super block write has failed, so users can expect potentially erroneous behaviour. It also forces wait_dev_supers() to return an error to its caller if the primary super block write fails. Signed-off-by: Howard McLauchlan Reviewed-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/disk-io.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 21f34ad..9f7ed43 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3290,6 +3290,7 @@ static int wait_dev_supers(struct btrfs_device *device, int max_mirrors) struct buffer_head *bh; int i; int errors = 0; + bool primary_failed = false; u64 bytenr; if (max_mirrors == 0) @@ -3306,11 +3307,16 @@ static int wait_dev_supers(struct btrfs_device *device, int max_mirrors) BTRFS_SUPER_INFO_SIZE); if (!bh) { errors++; + if (i == 0) + primary_failed = true; continue; } wait_on_buffer(bh); - if (!buffer_uptodate(bh)) + if (!buffer_uptodate(bh)) { errors++; + if (i == 0) + primary_failed = true; + } /* drop our reference */ brelse(bh); @@ -3319,6 +3325,13 @@ static int wait_dev_supers(struct btrfs_device *device, int max_mirrors) brelse(bh); } + /* log error, force error return */ + if (primary_failed) { + btrfs_err(device->fs_info, "error writing primary super block to device %llu", + device->devid); + return -1; + } + return errors < i ? 0 : -1; } -- 2.7.4