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.
==
Changes since v5:
1. Renamed MF_MEM_REMOVE to MF_MEM_PRE_REMOVE
2. hold s_umount before sync_filesystem()
3. move sync_filesystem() after SB_BORN check
4. Rebased on next-20220714
Changes since v4:
1. sync_filesystem() at the beginning when MF_MEM_REMOVE
2. Rebased on next-20220706
[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 | 15 +++++++++++++++
include/linux/mm.h | 1 +
3 files changed, 18 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 69d9c83ea4b2..6da6747435eb 100644
--- a/fs/xfs/xfs_notify_failure.c
+++ b/fs/xfs/xfs_notify_failure.c
@@ -76,6 +76,9 @@ xfs_dax_failure_fn(
if (XFS_RMAP_NON_INODE_OWNER(rec->rm_owner) ||
(rec->rm_flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK))) {
+ /* Do not shutdown so early when device is to be removed */
+ if (notify->mf_flags & MF_MEM_PRE_REMOVE)
+ return 0;
xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_ONDISK);
return -EFSCORRUPTED;
}
@@ -174,12 +177,22 @@ xfs_dax_notify_failure(
struct xfs_mount *mp = dax_holder(dax_dev);
u64 ddev_start;
u64 ddev_end;
+ int error;
if (!(mp->m_sb.sb_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);
+ 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_warn(mp,
"notify_failure() not supported on realtime device!");
@@ -188,6 +201,8 @@ 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;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 4287bec50c28..2ddfb76c8a83 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3188,6 +3188,7 @@ enum mf_flags {
MF_SOFT_OFFLINE = 1 << 3,
MF_UNPOISON = 1 << 4,
MF_SW_SIMULATED = 1 << 5,
+ MF_MEM_PRE_REMOVE = 1 << 6,
};
int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index,
unsigned long count, int mf_flags);
--
2.37.0
