| Message ID | 20180130223349.5808-1-hmclauchlan@fb.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2018年01月31日 06:33, Howard McLauchlan wrote: > 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 <hmclauchlan@fb.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Thanks, Qu > --- > V2: Added devid to output, removed unnecessary fs_info parameter > > fs/btrfs/disk-io.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index 5da18ebc9222..6d98f2f21d5f 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -3298,6 +3298,7 @@ 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) > @@ -3314,11 +3315,14 @@ static int wait_dev_supers(struct btrfs_device *device, int max_mirrors) > BTRFS_SUPER_INFO_SIZE); > if (!bh) { > errors++; > + primary_failed = (i == 0) || primary_failed; > continue; > } > wait_on_buffer(bh); > - if (!buffer_uptodate(bh)) > + if (!buffer_uptodate(bh)) { > errors++; > + primary_failed = (i == 0) || primary_failed; > + } > > /* drop our reference */ > brelse(bh); > @@ -3327,6 +3331,13 @@ 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; > } > >
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 5da18ebc9222..6d98f2f21d5f 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3298,6 +3298,7 @@ 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) @@ -3314,11 +3315,14 @@ static int wait_dev_supers(struct btrfs_device *device, int max_mirrors) BTRFS_SUPER_INFO_SIZE); if (!bh) { errors++; + primary_failed = (i == 0) || primary_failed; continue; } wait_on_buffer(bh); - if (!buffer_uptodate(bh)) + if (!buffer_uptodate(bh)) { errors++; + primary_failed = (i == 0) || primary_failed; + } /* drop our reference */ brelse(bh); @@ -3327,6 +3331,13 @@ 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; }
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 <hmclauchlan@fb.com> --- V2: Added devid to output, removed unnecessary fs_info parameter fs/btrfs/disk-io.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)