On Fri, Sep 02, 2022 at 10:36:01AM +0000, Shiyang Ruan wrote: > 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); > + } I wonder, won't the trimming code below take care of this? The rest of the patch looks ok to me. --D > + > /* 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 >
