The patch titled
Subject: fsdax: hold dax lock over mapping insertion
has been added to the -mm mm-unstable branch. Its filename is
fsdax-hold-dax-lock-over-mapping-insertion.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fsdax-hold-dax-lock-over-mapping-insertion.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Dan Williams <dan.j.williams@xxxxxxxxx>
Subject: fsdax: hold dax lock over mapping insertion
Date: Fri, 14 Oct 2022 16:57:37 -0700
In preparation for dax_insert_entry() to start taking page and pgmap
references ensure that page->pgmap is valid by holding the dax_read_lock()
over both dax_direct_access() and dax_insert_entry().
I.e. the code that wants to elevate the reference count of a pgmap page
from 0 -> 1 must ensure that the pgmap is not exiting and will not start
exiting until the proper references have been taken.
Link: https://lkml.kernel.org/r/166579185727.2236710.8711235794537270051.stgit@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: "Darrick J. Wong" <djwong@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
Cc: "Christian König" <christian.koenig@xxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: Karol Herbst <kherbst@xxxxxxxxxx>
Cc: kernel test robot <lkp@xxxxxxxxx>
Cc: Lyude Paul <lyude@xxxxxxxxxx>
Cc: "Pan, Xinhui" <Xinhui.Pan@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/dax.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
--- a/fs/dax.c~fsdax-hold-dax-lock-over-mapping-insertion
+++ a/fs/dax.c
@@ -1107,10 +1107,9 @@ static int dax_iomap_direct_access(const
size_t size, void **kaddr, pfn_t *pfnp)
{
pgoff_t pgoff = dax_iomap_pgoff(iomap, pos);
- int id, rc = 0;
long length;
+ int rc = 0;
- id = dax_read_lock();
length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
DAX_ACCESS, kaddr, pfnp);
if (length < 0) {
@@ -1135,7 +1134,6 @@ out_check_addr:
if (!*kaddr)
rc = -EFAULT;
out:
- dax_read_unlock(id);
return rc;
}
@@ -1591,7 +1589,7 @@ static vm_fault_t dax_fault_iter(struct
loff_t pos = (loff_t)xas->xa_index << PAGE_SHIFT;
bool write = iter->flags & IOMAP_WRITE;
unsigned long entry_flags = pmd ? DAX_PMD : 0;
- int err = 0;
+ int err = 0, id;
pfn_t pfn;
void *kaddr;
@@ -1611,11 +1609,15 @@ static vm_fault_t dax_fault_iter(struct
return pmd ? VM_FAULT_FALLBACK : VM_FAULT_SIGBUS;
}
+ id = dax_read_lock();
err = dax_iomap_direct_access(iomap, pos, size, &kaddr, &pfn);
- if (err)
+ if (err) {
+ dax_read_unlock(id);
return pmd ? VM_FAULT_FALLBACK : dax_fault_return(err);
+ }
*entry = dax_insert_entry(xas, vmf, iter, *entry, pfn, entry_flags);
+ dax_read_unlock(id);
if (write &&
srcmap->type != IOMAP_HOLE && srcmap->addr != iomap->addr) {
_
Patches currently in -mm which might be from dan.j.williams@xxxxxxxxx are
fsdax-wait-on-page-not-page-_refcount.patch
fsdax-use-dax_page_idle-to-document-dax-busy-page-checking.patch
fsdax-include-unmapped-inodes-for-page-idle-detection.patch
fsdax-introduce-dax_zap_mappings.patch
fsdax-wait-for-pinned-pages-during-truncate_inode_pages_final.patch
fsdax-validate-dax-layouts-broken-before-truncate.patch
fsdax-hold-dax-lock-over-mapping-insertion.patch
fsdax-update-dax_insert_entry-calling-convention-to-return-an-error.patch
fsdax-rework-for_each_mapped_pfn-to-dax_for_each_folio.patch
fsdax-introduce-pgmap_request_folios.patch
fsdax-rework-dax_insert_entry-calling-convention.patch
fsdax-cleanup-dax_associate_entry.patch
devdax-minor-warning-fixups.patch
devdax-fix-sparse-lock-imbalance-warning.patch
libnvdimm-pmem-support-pmem-block-devices-without-dax.patch
devdax-move-address_space-helpers-to-the-dax-core.patch
devdax-sparse-fixes-for-xarray-locking.patch
devdax-sparse-fixes-for-vmfault_t-dax-entry-conversions.patch
devdax-sparse-fixes-for-vm_fault_t-in-tracepoints.patch
devdax-add-pud-support-to-the-dax-mapping-infrastructure.patch
devdax-use-dax_insert_entry-dax_delete_mapping_entry.patch
mm-memremap_pages-replace-zone_device_page_init-with-pgmap_request_folios.patch
mm-memremap_pages-initialize-all-zone_device-pages-to-start-at-refcount-0.patch
mm-meremap_pages-delete-put_devmap_managed_page_refs.patch
mm-gup-drop-dax-pgmap-accounting.patch
