This patch is inspired by Dan's "mm, dax, pmem: Introduce
dev_pagemap_failure()"[1]. With the help of dax_holder and
->notify_failure() mechanism, the pmem driver is able to ask filesystem
(or mapped device) on it to unmap all files in use and notify processes
who are using those files.
Call trace:
trigger unbind
-> unbind_store()
-> ... (skip)
-> devres_release_all() # was pmem driver ->remove() in v1
-> kill_dax()
-> dax_holder_notify_failure(dax_dev, 0, U64_MAX, MF_MEM_PRE_REMOVE)
-> xfs_dax_notify_failure()
Introduce MF_MEM_PRE_REMOVE to let filesystem know this is a remove
event. So do not shutdown filesystem directly if something not
supported, or if failure range includes metadata area. Make sure all
files and processes are handled correctly.
[1]: https://lore.kernel.org/linux-mm/161604050314.1463742.14151665140035795571.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>
---
drivers/dax/super.c | 3 ++-
fs/xfs/xfs_notify_failure.c | 23 +++++++++++++++++++++++
include/linux/mm.h | 1 +
3 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 9b5e2a5eb0ae..cf9a64563fbe 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -323,7 +323,8 @@ void kill_dax(struct dax_device *dax_dev)
return;
if (dax_dev->holder_data != NULL)
- dax_holder_notify_failure(dax_dev, 0, U64_MAX, 0);
+ dax_holder_notify_failure(dax_dev, 0, U64_MAX,
+ MF_MEM_PRE_REMOVE);
clear_bit(DAXDEV_ALIVE, &dax_dev->flags);
synchronize_srcu(&dax_srcu);
diff --git a/fs/xfs/xfs_notify_failure.c b/fs/xfs/xfs_notify_failure.c
index 3830f908e215..5e04ba7fa403 100644
--- a/fs/xfs/xfs_notify_failure.c
+++ b/fs/xfs/xfs_notify_failure.c
@@ -22,6 +22,7 @@
#include <linux/mm.h>
#include <linux/dax.h>
+#include <linux/fs.h>
struct xfs_failure_info {
xfs_agblock_t startblock;
@@ -77,6 +78,9 @@ xfs_dax_failure_fn(
if (XFS_RMAP_NON_INODE_OWNER(rec->rm_owner) ||
(rec->rm_flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK))) {
+ /* The device is about to be removed. Not a really failure. */
+ if (notify->mf_flags & MF_MEM_PRE_REMOVE)
+ return 0;
notify->want_shutdown = true;
return 0;
}
@@ -182,12 +186,23 @@ xfs_dax_notify_failure(
struct xfs_mount *mp = dax_holder(dax_dev);
u64 ddev_start;
u64 ddev_end;
+ int error;
if (!(mp->m_super->s_flags & SB_BORN)) {
xfs_warn(mp, "filesystem is not ready for notify_failure()!");
return -EIO;
}
+ if (mf_flags & MF_MEM_PRE_REMOVE) {
+ xfs_info(mp, "device is about to be removed!");
+ down_write(&mp->m_super->s_umount);
+ error = sync_filesystem(mp->m_super);
+ drop_pagecache_sb(mp->m_super, NULL);
+ up_write(&mp->m_super->s_umount);
+ if (error)
+ return error;
+ }
+
if (mp->m_rtdev_targp && mp->m_rtdev_targp->bt_daxdev == dax_dev) {
xfs_debug(mp,
"notify_failure() not supported on realtime device!");
@@ -196,6 +211,8 @@ xfs_dax_notify_failure(
if (mp->m_logdev_targp && mp->m_logdev_targp->bt_daxdev == dax_dev &&
mp->m_logdev_targp != mp->m_ddev_targp) {
+ if (mf_flags & MF_MEM_PRE_REMOVE)
+ return 0;
xfs_err(mp, "ondisk log corrupt, shutting down fs!");
xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_ONDISK);
return -EFSCORRUPTED;
@@ -209,6 +226,12 @@ xfs_dax_notify_failure(
ddev_start = mp->m_ddev_targp->bt_dax_part_off;
ddev_end = ddev_start + bdev_nr_bytes(mp->m_ddev_targp->bt_bdev) - 1;
+ /* Notify failure on the whole device */
+ if (offset == 0 && len == U64_MAX) {
+ offset = ddev_start;
+ len = bdev_nr_bytes(mp->m_ddev_targp->bt_bdev);
+ }
