This function is used to handle errors which may cause data lost in
filesystem.  Such as memory failure in fsdax mode.

If the rmap feature of XFS enabled, we can query it to find files and
metadata which are associated with the corrupt data.  For now all we do
is kill processes with that file mapped into their address spaces, but
future patches could actually do something about corrupt metadata.

After that, the memory failure needs to notify the processes who are
using those files.

Only support data device.  Realtime device is not supported for now.

Signed-off-by: Shiyang Ruan <[email protected]>
---
 fs/xfs/xfs_fsops.c |   5 ++
 fs/xfs/xfs_mount.h |   1 +
 fs/xfs/xfs_super.c | 140 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 146 insertions(+)

diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index be9cf88d2ad7..e89ada33d8fc 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -551,6 +551,11 @@ xfs_do_force_shutdown(
 "Corruption of in-memory data detected.  Shutting down filesystem");
                if (XFS_ERRLEVEL_HIGH <= xfs_error_level)
                        xfs_stack_trace();
+       } else if (flags & SHUTDOWN_CORRUPT_META) {
+               xfs_alert_tag(mp, XFS_PTAG_SHUTDOWN_CORRUPT,
+"Corruption of on-disk metadata detected.  Shutting down filesystem");
+               if (XFS_ERRLEVEL_HIGH <= xfs_error_level)
+                       xfs_stack_trace();
        } else if (logerror) {
                xfs_alert_tag(mp, XFS_PTAG_SHUTDOWN_LOGERROR,
                        "Log I/O Error Detected. Shutting down filesystem");
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index bb67274ee23f..c62ccf3e07d0 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -276,6 +276,7 @@ void xfs_do_force_shutdown(struct xfs_mount *mp, int flags, 
char *fname,
 #define SHUTDOWN_LOG_IO_ERROR  0x0002  /* write attempt to the log failed */
 #define SHUTDOWN_FORCE_UMOUNT  0x0004  /* shutdown from a forced unmount */
 #define SHUTDOWN_CORRUPT_INCORE        0x0008  /* corrupt in-memory data 
structures */
+#define SHUTDOWN_CORRUPT_META  0x0010  /* corrupt metadata on device */

 /*
  * Flags for xfs_mountfs
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index a2dab05332ac..a986ddf3b248 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -36,11 +36,18 @@
 #include "xfs_bmap_item.h"
 #include "xfs_reflink.h"
 #include "xfs_pwork.h"
+#include "xfs_alloc.h"
+#include "xfs_rmap.h"
+#include "xfs_rmap_btree.h"
+#include "xfs_rtalloc.h"
+#include "xfs_bit.h"

 #include <linux/magic.h>
 #include <linux/fs_context.h>
 #include <linux/fs_parser.h>
+#include <linux/mm.h>

+static const struct dax_holder_operations xfs_dax_holder_operations;
 static const struct super_operations xfs_super_operations;

 static struct kset *xfs_kset;          /* top-level xfs sysfs dir */
@@ -358,6 +365,7 @@ xfs_close_devices(

                xfs_free_buftarg(mp->m_logdev_targp);
                xfs_blkdev_put(logdev);
+               dax_set_holder(dax_logdev, NULL, NULL);
                fs_put_dax(dax_logdev);
        }
        if (mp->m_rtdev_targp) {
@@ -366,9 +374,11 @@ xfs_close_devices(

                xfs_free_buftarg(mp->m_rtdev_targp);
                xfs_blkdev_put(rtdev);
+               dax_set_holder(dax_rtdev, NULL, NULL);
                fs_put_dax(dax_rtdev);
        }
        xfs_free_buftarg(mp->m_ddev_targp);
+       dax_set_holder(dax_ddev, NULL, NULL);
        fs_put_dax(dax_ddev);
 }

@@ -392,6 +402,7 @@ xfs_open_devices(
        struct block_device     *logdev = NULL, *rtdev = NULL;
        int                     error;

+       dax_set_holder(dax_ddev, mp, &xfs_dax_holder_operations);
        /*
         * Open real time and log devices - order is important.
         */
@@ -400,6 +411,9 @@ xfs_open_devices(
                if (error)
                        goto out;
                dax_logdev = fs_dax_get_by_bdev(logdev);
+               if (dax_logdev != dax_ddev)
+                       dax_set_holder(dax_logdev, mp,
+                                      &xfs_dax_holder_operations);
        }

        if (mp->m_rtname) {
@@ -414,6 +428,7 @@ xfs_open_devices(
                        goto out_close_rtdev;
                }
                dax_rtdev = fs_dax_get_by_bdev(rtdev);
+               dax_set_holder(dax_rtdev, mp, &xfs_dax_holder_operations);
        }

        /*
@@ -1076,6 +1091,131 @@ xfs_fs_free_cached_objects(
        return xfs_reclaim_inodes_nr(XFS_M(sb), sc->nr_to_scan);
 }

+static int
+xfs_corrupt_helper(
+       struct xfs_btree_cur            *cur,
+       struct xfs_rmap_irec            *rec,
+       void                            *data)
+{
+       struct xfs_inode                *ip;
+       struct address_space            *mapping;
+       int                             error = 0;
+       int                             *flags = data;
+
+       if (XFS_RMAP_NON_INODE_OWNER(rec->rm_owner) ||
+           (rec->rm_flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK))) {
+               // TODO check and try to fix metadata
+               xfs_force_shutdown(cur->bc_mp, SHUTDOWN_CORRUPT_META);
+               return -EFSCORRUPTED;
+       }
+
+       /*
+        * Get files that incore, filter out others that are not in use.
+        */
+       error = xfs_iget(cur->bc_mp, cur->bc_tp, rec->rm_owner, XFS_IGET_INCORE,
+                       0, &ip);
+       if (error)
+               return error;
+
+       mapping = VFS_I(ip)->i_mapping;
+
+#ifdef CONFIG_MEMORY_FAILURE
+       error = mf_dax_kill_procs(mapping, rec->rm_offset, *flags);
+#endif
+
+       // TODO try to fix data
+       xfs_irele(ip);
+
+       return error;
+}
+
+static loff_t
+xfs_dax_bdev_offset(
+       struct xfs_mount *mp,
+       struct dax_device *dax_dev,
+       loff_t disk_offset)
+{
+       struct block_device *bdev;
+
+       if (mp->m_ddev_targp->bt_daxdev == dax_dev)
+               bdev = mp->m_ddev_targp->bt_bdev;
+       else if (mp->m_logdev_targp->bt_daxdev == dax_dev)
+               bdev = mp->m_logdev_targp->bt_bdev;
+       else
+               bdev = mp->m_rtdev_targp->bt_bdev;
+
+       return disk_offset - (get_start_sect(bdev) << SECTOR_SHIFT);
+}
+
+static int
+xfs_dax_notify_failure(
+       struct dax_device       *dax_dev,
+       loff_t                  offset,
+       size_t                  len,
+       void                    *data)
+{
+       struct xfs_mount        *mp = dax_get_holder(dax_dev);
+       struct xfs_trans        *tp = NULL;
+       struct xfs_btree_cur    *cur = NULL;
+       struct xfs_buf          *agf_bp = NULL;
+       struct xfs_rmap_irec    rmap_low, rmap_high;
+       loff_t                  bdev_offset = xfs_dax_bdev_offset(mp, dax_dev,
+                                                                 offset);
+       xfs_fsblock_t           fsbno = XFS_B_TO_FSB(mp, bdev_offset);
+       xfs_filblks_t           bcnt = XFS_B_TO_FSB(mp, len);
+       xfs_agnumber_t          agno = XFS_FSB_TO_AGNO(mp, fsbno);
+       xfs_agblock_t           agbno = XFS_FSB_TO_AGBNO(mp, fsbno);
+       int                     error = 0;
+
+       pr_warn("%s bno: %lld\n", __func__, bdev_offset >> SECTOR_SHIFT);
+
+       if (mp->m_rtdev_targp && mp->m_rtdev_targp->bt_daxdev == dax_dev) {
+               xfs_warn(mp, "corrupted_range support not available for 
realtime device!");
+               return -EOPNOTSUPP;
+       }
+       if (mp->m_logdev_targp && mp->m_logdev_targp->bt_daxdev == dax_dev &&
+           mp->m_logdev_targp != mp->m_ddev_targp) {
+               xfs_err(mp, "ondisk log corrupt, shutting down fs!");
+               xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_META);
+               return -EFSCORRUPTED;
+       }
+
+       if (!xfs_sb_version_hasrmapbt(&mp->m_sb)) {
+               xfs_warn(mp, "corrupted_range needs rmapbt enabled!");
+               return -EOPNOTSUPP;
+       }
+
+       error = xfs_trans_alloc_empty(mp, &tp);
+       if (error)
+               return error;
+
+       error = xfs_alloc_read_agf(mp, tp, agno, 0, &agf_bp);
+       if (error)
+               goto out_cancel_tp;
+
+       cur = xfs_rmapbt_init_cursor(mp, tp, agf_bp, agno);
+
+       /* Construct a range for rmap query */
+       memset(&rmap_low, 0, sizeof(rmap_low));
+       memset(&rmap_high, 0xFF, sizeof(rmap_high));
+       rmap_low.rm_startblock = rmap_high.rm_startblock = agbno;
+       rmap_low.rm_blockcount = rmap_high.rm_blockcount = bcnt;
+
+       error = xfs_rmap_query_range(cur, &rmap_low, &rmap_high,
+                                    xfs_corrupt_helper, data);
+
+       xfs_btree_del_cursor(cur, error);
+       xfs_trans_brelse(tp, agf_bp);
+
+out_cancel_tp:
+       xfs_trans_cancel(tp);
+       return error;
+}
+
+static const struct dax_holder_operations xfs_dax_holder_operations = {
+       .notify_failure = xfs_dax_notify_failure,
+};
+
 static const struct super_operations xfs_super_operations = {
        .alloc_inode            = xfs_fs_alloc_inode,
        .destroy_inode          = xfs_fs_destroy_inode,
--
2.32.0



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