[PATCH 3/3] mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind
From: Shiyang Ruan <hidden>
Date: 2022-09-02 10:36:48
Also in:
linux-fsdevel, linux-mm, lkml, nvdimm
Subsystem:
device direct access (dax), filesystems (vfs and infrastructure), memory management - core, the rest, xfs filesystem · Maintainers:
Dan Williams, Vishal Verma, Dave Jiang, Alison Schofield, Alexander Viro, Christian Brauner, Andrew Morton, David Hildenbrand, Linus Torvalds, Carlos Maiolino
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@dwillia2-desk3.amr.corp.intel.com/ (local)
Signed-off-by: Shiyang Ruan <redacted>
---
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); + } + /* Ignore the range out of filesystem area */ if (offset + len - 1 < ddev_start) return -ENXIO;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 21f8b27bd9fd..9122a1c57dd2 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -3183,6 +3183,7 @@ enum mf_flags { MF_UNPOISON = 1 << 4, MF_SW_SIMULATED = 1 << 5, MF_NO_RETRY = 1 << 6, + MF_MEM_PRE_REMOVE = 1 << 7, }; int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index, unsigned long count, int mf_flags);
--
2.37.2