| Message ID | 161404926616.425602.16421331298021628773.stgit@magnolia (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
| Series | xfs_repair: set needsrepair when dirtying filesystems | expand |
On 2/22/21 8:01 PM, Darrick J. Wong wrote: > From: Darrick J. Wong <djwong@kernel.org> > > Add a hook to the buffer cache so that xfs_repair can intercept the > first write to a V5 filesystem to set the NEEDSREPAIR flag. In the > event that xfs_repair dirties the filesystem and goes down, this ensures > that the sysadmin will have to re-start repair before mounting. > > Signed-off-by: Darrick J. Wong <djwong@kernel.org> > Reviewed-by: Brian Foster <bfoster@redhat.com> Ok, I think it looks good Reviewed-by: Allison Henderson <allison.henderson@oracle.com> > --- > include/xfs_mount.h | 4 ++ > libxfs/rdwr.c | 4 ++ > repair/xfs_repair.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 110 insertions(+) > > > diff --git a/include/xfs_mount.h b/include/xfs_mount.h > index 75230ca5..f93a9f11 100644 > --- a/include/xfs_mount.h > +++ b/include/xfs_mount.h > @@ -11,6 +11,8 @@ struct xfs_inode; > struct xfs_buftarg; > struct xfs_da_geometry; > > +typedef void (*buf_writeback_fn)(struct xfs_buf *bp); > + > /* > * Define a user-level mount structure with all we need > * in order to make use of the numerous XFS_* macros. > @@ -95,6 +97,8 @@ typedef struct xfs_mount { > int qi_dqperchunk; > } *m_quotainfo; > > + buf_writeback_fn m_buf_writeback_fn; > + > /* > * xlog is defined in libxlog and thus is not intialized by libxfs. This > * allows an application to initialize and store a reference to the log > diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c > index ac783ce3..ca272387 100644 > --- a/libxfs/rdwr.c > +++ b/libxfs/rdwr.c > @@ -812,6 +812,10 @@ libxfs_bwrite( > return bp->b_error; > } > > + /* Trigger the writeback hook if there is one. */ > + if (bp->b_mount->m_buf_writeback_fn) > + bp->b_mount->m_buf_writeback_fn(bp); > + > /* > * clear any pre-existing error status on the buffer. This can occur if > * the buffer is corrupt on disk and the repair process doesn't clear > diff --git a/repair/xfs_repair.c b/repair/xfs_repair.c > index e2e99b21..03b7c242 100644 > --- a/repair/xfs_repair.c > +++ b/repair/xfs_repair.c > @@ -751,6 +751,104 @@ clear_needsrepair( > libxfs_buf_relse(bp); > } > > +static void > +update_sb_crc_only( > + struct xfs_buf *bp) > +{ > + xfs_buf_update_cksum(bp, XFS_SB_CRC_OFF); > +} > + > +/* Forcibly write the primary superblock with the NEEDSREPAIR flag set. */ > +static void > +force_needsrepair( > + struct xfs_mount *mp) > +{ > + struct xfs_buf_ops fake_ops; > + struct xfs_buf *bp; > + int error; > + > + if (!xfs_sb_version_hascrc(&mp->m_sb) || > + xfs_sb_version_needsrepair(&mp->m_sb)) > + return; > + > + bp = libxfs_getsb(mp); > + if (!bp || bp->b_error) { > + do_log( > + _("couldn't get superblock to set needsrepair, err=%d\n"), > + bp ? bp->b_error : ENOMEM); > + } else { > + /* > + * It's possible that we need to set NEEDSREPAIR before we've > + * had a chance to fix the summary counters in the primary sb. > + * With the exception of those counters, phase 1 already > + * ensured that the geometry makes sense. > + * > + * Bad summary counters in the primary super can cause the > + * write verifier to fail, so substitute a dummy that only sets > + * the CRC. In the event of a crash, NEEDSREPAIR will prevent > + * the kernel from mounting our potentially damaged filesystem > + * until repair is run again, so it's ok to bypass the usual > + * verification in this one case. > + */ > + fake_ops = xfs_sb_buf_ops; /* struct copy */ > + fake_ops.verify_write = update_sb_crc_only; > + > + mp->m_sb.sb_features_incompat |= > + XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR; > + libxfs_sb_to_disk(bp->b_addr, &mp->m_sb); > + > + /* Force the primary super to disk immediately. */ > + bp->b_ops = &fake_ops; > + error = -libxfs_bwrite(bp); > + bp->b_ops = &xfs_sb_buf_ops; > + if (error) > + do_log(_("couldn't force needsrepair, err=%d\n"), error); > + } > + if (bp) > + libxfs_buf_relse(bp); > +} > + > +/* > + * Intercept the first non-super write to the filesystem so we can set > + * NEEDSREPAIR to protect the filesystem from mount in case of a crash. > + */ > +static void > +repair_capture_writeback( > + struct xfs_buf *bp) > +{ > + struct xfs_mount *mp = bp->b_mount; > + static pthread_mutex_t wb_mutex = PTHREAD_MUTEX_INITIALIZER; > + > + /* > + * This write hook ignores any buffer that looks like a superblock to > + * avoid hook recursion when setting NEEDSREPAIR. Higher level code > + * modifying an sb must control the flag manually. > + */ > + if (bp->b_ops == &xfs_sb_buf_ops || bp->b_bn == XFS_SB_DADDR) > + return; > + > + pthread_mutex_lock(&wb_mutex); > + > + /* > + * If someone else already dropped the hook, then needsrepair has > + * already been set on the filesystem and we can unlock. > + */ > + if (mp->m_buf_writeback_fn != repair_capture_writeback) > + goto unlock; > + > + /* > + * If we get here, the buffer being written is not a superblock, and > + * needsrepair needs to be set. The hook is kept in place to plug all > + * other writes until the sb write finishes. > + */ > + force_needsrepair(mp); > + > + /* We only set needsrepair once, so clear the hook now. */ > + mp->m_buf_writeback_fn = NULL; > +unlock: > + pthread_mutex_unlock(&wb_mutex); > +} > + > int > main(int argc, char **argv) > { > @@ -847,6 +945,10 @@ main(int argc, char **argv) > if (verbose > 2) > mp->m_flags |= LIBXFS_MOUNT_WANT_CORRUPTED; > > + /* Capture the first writeback so that we can set needsrepair. */ > + if (xfs_sb_version_hascrc(&mp->m_sb)) > + mp->m_buf_writeback_fn = repair_capture_writeback; > + > /* > * set XFS-independent status vars from the mount/sb structure > */ >
> diff --git a/include/xfs_mount.h b/include/xfs_mount.h > index 75230ca5..f93a9f11 100644 > --- a/include/xfs_mount.h > +++ b/include/xfs_mount.h > @@ -11,6 +11,8 @@ struct xfs_inode; > struct xfs_buftarg; > struct xfs_da_geometry; > > +typedef void (*buf_writeback_fn)(struct xfs_buf *bp); Any point in adding a typedef that is only used once? > + if (!bp || bp->b_error) { > + do_log( > + _("couldn't get superblock to set needsrepair, err=%d\n"), > + bp ? bp->b_error : ENOMEM); Maybe add a goto out_buf_release goto here to avoid the extra level of indentation for the normal path? But the code itself looks good, so: Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/include/xfs_mount.h b/include/xfs_mount.h index 75230ca5..f93a9f11 100644 --- a/include/xfs_mount.h +++ b/include/xfs_mount.h @@ -11,6 +11,8 @@ struct xfs_inode; struct xfs_buftarg; struct xfs_da_geometry; +typedef void (*buf_writeback_fn)(struct xfs_buf *bp); + /* * Define a user-level mount structure with all we need * in order to make use of the numerous XFS_* macros. @@ -95,6 +97,8 @@ typedef struct xfs_mount { int qi_dqperchunk; } *m_quotainfo; + buf_writeback_fn m_buf_writeback_fn; + /* * xlog is defined in libxlog and thus is not intialized by libxfs. This * allows an application to initialize and store a reference to the log diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c index ac783ce3..ca272387 100644 --- a/libxfs/rdwr.c +++ b/libxfs/rdwr.c @@ -812,6 +812,10 @@ libxfs_bwrite( return bp->b_error; } + /* Trigger the writeback hook if there is one. */ + if (bp->b_mount->m_buf_writeback_fn) + bp->b_mount->m_buf_writeback_fn(bp); + /* * clear any pre-existing error status on the buffer. This can occur if * the buffer is corrupt on disk and the repair process doesn't clear diff --git a/repair/xfs_repair.c b/repair/xfs_repair.c index e2e99b21..03b7c242 100644 --- a/repair/xfs_repair.c +++ b/repair/xfs_repair.c @@ -751,6 +751,104 @@ clear_needsrepair( libxfs_buf_relse(bp); } +static void +update_sb_crc_only( + struct xfs_buf *bp) +{ + xfs_buf_update_cksum(bp, XFS_SB_CRC_OFF); +} + +/* Forcibly write the primary superblock with the NEEDSREPAIR flag set. */ +static void +force_needsrepair( + struct xfs_mount *mp) +{ + struct xfs_buf_ops fake_ops; + struct xfs_buf *bp; + int error; + + if (!xfs_sb_version_hascrc(&mp->m_sb) || + xfs_sb_version_needsrepair(&mp->m_sb)) + return; + + bp = libxfs_getsb(mp); + if (!bp || bp->b_error) { + do_log( + _("couldn't get superblock to set needsrepair, err=%d\n"), + bp ? bp->b_error : ENOMEM); + } else { + /* + * It's possible that we need to set NEEDSREPAIR before we've + * had a chance to fix the summary counters in the primary sb. + * With the exception of those counters, phase 1 already + * ensured that the geometry makes sense. + * + * Bad summary counters in the primary super can cause the + * write verifier to fail, so substitute a dummy that only sets + * the CRC. In the event of a crash, NEEDSREPAIR will prevent + * the kernel from mounting our potentially damaged filesystem + * until repair is run again, so it's ok to bypass the usual + * verification in this one case. + */ + fake_ops = xfs_sb_buf_ops; /* struct copy */ + fake_ops.verify_write = update_sb_crc_only; + + mp->m_sb.sb_features_incompat |= + XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR; + libxfs_sb_to_disk(bp->b_addr, &mp->m_sb); + + /* Force the primary super to disk immediately. */ + bp->b_ops = &fake_ops; + error = -libxfs_bwrite(bp); + bp->b_ops = &xfs_sb_buf_ops; + if (error) + do_log(_("couldn't force needsrepair, err=%d\n"), error); + } + if (bp) + libxfs_buf_relse(bp); +} + +/* + * Intercept the first non-super write to the filesystem so we can set + * NEEDSREPAIR to protect the filesystem from mount in case of a crash. + */ +static void +repair_capture_writeback( + struct xfs_buf *bp) +{ + struct xfs_mount *mp = bp->b_mount; + static pthread_mutex_t wb_mutex = PTHREAD_MUTEX_INITIALIZER; + + /* + * This write hook ignores any buffer that looks like a superblock to + * avoid hook recursion when setting NEEDSREPAIR. Higher level code + * modifying an sb must control the flag manually. + */ + if (bp->b_ops == &xfs_sb_buf_ops || bp->b_bn == XFS_SB_DADDR) + return; + + pthread_mutex_lock(&wb_mutex); + + /* + * If someone else already dropped the hook, then needsrepair has + * already been set on the filesystem and we can unlock. + */ + if (mp->m_buf_writeback_fn != repair_capture_writeback) + goto unlock; + + /* + * If we get here, the buffer being written is not a superblock, and + * needsrepair needs to be set. The hook is kept in place to plug all + * other writes until the sb write finishes. + */ + force_needsrepair(mp); + + /* We only set needsrepair once, so clear the hook now. */ + mp->m_buf_writeback_fn = NULL; +unlock: + pthread_mutex_unlock(&wb_mutex); +} + int main(int argc, char **argv) { @@ -847,6 +945,10 @@ main(int argc, char **argv) if (verbose > 2) mp->m_flags |= LIBXFS_MOUNT_WANT_CORRUPTED; + /* Capture the first writeback so that we can set needsrepair. */ + if (xfs_sb_version_hascrc(&mp->m_sb)) + mp->m_buf_writeback_fn = repair_capture_writeback; + /* * set XFS-independent status vars from the mount/sb structure */