linux.git/fs/dax.c, branch v5.12

mm: provide a saner PTE walking API for modules

2021-02-09T12:05:44+00:00

Currently, the follow_pfn function is exported for modules but
follow_pte is not.  However, follow_pfn is very easy to misuse,
because it does not provide protections (so most of its callers
assume the page is writable!) and because it returns after having
already unlocked the page table lock.

Provide instead a simplified version of follow_pte that does
not have the pmdpp and range arguments.  The older version
survives as follow_invalidate_pte() for use by fs/dax.c.

Reviewed-by: Jason Gunthorpe 
Signed-off-by: Paolo Bonzini

mm: simplify follow_pte{,pmd}

2020-12-16T06:46:19+00:00

Merge __follow_pte_pmd, follow_pte_pmd and follow_pte into a single
follow_pte function and just pass two additional NULL arguments for the
two previous follow_pte callers.

[sfr@canb.auug.org.au: merge fix for "s390/pci: remove races against pte updates"]
  Link: https://lkml.kernel.org/r/20201111221254.7f6a3658@canb.auug.org.au

Link: https://lkml.kernel.org/r/20201029101432.47011-3-hch@lst.de
Signed-off-by: Christoph Hellwig 
Reviewed-by: Matthew Wilcox (Oracle) 
Cc: Daniel Vetter 
Cc: Dan Williams 
Cc: Nick Desaulniers 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'fuse-update-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse

2020-10-19T21:28:30+00:00

Pull fuse updates from Miklos Szeredi:

- Support directly accessing host page cache from virtiofs. This can
improve I/O performance for various workloads, as well as reducing
the memory requirement by eliminating double caching. Thanks to Vivek
Goyal for doing most of the work on this.

- Allow automatic submounting inside virtiofs. This allows unique
st_dev/ st_ino values to be assigned inside the guest to files
residing on different filesystems on the host. Thanks to Max Reitz
for the patches.

- Fix an old use after free bug found by Pradeep P V K.

* tag 'fuse-update-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (25 commits)
virtiofs: calculate number of scatter-gather elements accurately
fuse: connection remove fix
fuse: implement crossmounts
fuse: Allow fuse_fill_super_common() for submounts
fuse: split fuse_mount off of fuse_conn
fuse: drop fuse_conn parameter where possible
fuse: store fuse_conn in fuse_req
fuse: add submount support to
fuse: fix page dereference after free
virtiofs: add logic to free up a memory range
virtiofs: maintain a list of busy elements
virtiofs: serialize truncate/punch_hole and dax fault path
virtiofs: define dax address space operations
virtiofs: add DAX mmap support
virtiofs: implement dax read/write operations
virtiofs: introduce setupmapping/removemapping commands
virtiofs: implement FUSE_INIT map_alignment field
virtiofs: keep a list of free dax memory ranges
virtiofs: add a mount option to enable dax
virtiofs: set up virtio_fs dax_device
...

iomap: Change calling convention for zeroing

2020-09-21T15:59:27+00:00

Pass the full length to iomap_zero() and dax_iomap_zero(), and have
them return how many bytes they actually handled.  This is preparatory
work for handling THP, although it looks like DAX could actually take
advantage of it if there's a larger contiguous area.

Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong 
Reviewed-by: Christoph Hellwig

dax: Create a range version of dax_layout_busy_page()

2020-09-10T09:39:22+00:00

virtiofs device has a range of memory which is mapped into file inodes
using dax. This memory is mapped in qemu on host and maps different
sections of real file on host. Size of this memory is limited
(determined by administrator) and depending on filesystem size, we will
soon reach a situation where all the memory is in use and we need to
reclaim some.

As part of reclaim process, we will need to make sure that there are
no active references to pages (taken by get_user_pages()) on the memory
range we are trying to reclaim. I am planning to use
dax_layout_busy_page() for this. But in current form this is per inode
and scans through all the pages of the inode.

We want to reclaim only a portion of memory (say 2MB page). So we want
to make sure that only that 2MB range of pages do not have any
references  (and don't want to unmap all the pages of inode).

Hence, create a range version of this function named
dax_layout_busy_page_range() which can be used to pass a range which
needs to be unmapped.

Cc: Dan Williams 
Cc: linux-nvdimm@lists.01.org
Cc: Jan Kara 
Cc: Vishal L Verma 
Cc: "Weiny, Ira" 
Signed-off-by: Vivek Goyal 
Reviewed-by: Jan Kara 
Signed-off-by: Miklos Szeredi

treewide: Use fallthrough pseudo-keyword

2020-08-23T22:36:59+00:00

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva

dax: Fix incorrect argument passed to xas_set_err()

2020-07-31T00:14:33+00:00

The argument passed to xas_set_err() to indicate an error should be negative.
Otherwise, xas_error() will return 0, and grab_mapping_entry() will return the
found entry instead of 'SIGBUS' when the entry is not in fact valid.
This would result in problems in subsequent code paths.

Link: https://lore.kernel.org/r/20200729034436.24267-1-lihao2018.fnst@cn.fujitsu.com
Reviewed-by: Pankaj Gupta 
Signed-off-by: Hao Li 
Signed-off-by: Vishal Verma

fs/dax: Remove unused size parameter

2020-07-28T17:49:29+00:00

Passing size to copy_user_dax implies it can copy variable sizes of data
when in fact it calls copy_user_page() which is exactly a page.

We are safe because the only caller uses PAGE_SIZE anyway so just remove
the variable for clarity.

While we are at it change copy_user_dax() to copy_cow_page_dax() to make
it clear it is a singleton helper for this one case not implementing
what dax_iomap_actor() does.

Link: https://lore.kernel.org/r/20200717072056.73134-11-ira.weiny@intel.com
Reviewed-by: Ben Widawsky 
Reviewed-by: Dan Williams 
Signed-off-by: Ira Weiny 
Signed-off-by: Vishal Verma

dax,iomap: Add helper dax_iomap_zero() to zero a range

2020-04-03T02:15:03+00:00

Add a helper dax_ioamp_zero() to zero a range. This patch basically
merges __dax_zero_page_range() and iomap_dax_zero().

Suggested-by: Christoph Hellwig 
Signed-off-by: Vivek Goyal 
Reviewed-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20200228163456.1587-7-vgoyal@redhat.com
Signed-off-by: Dan Williams

dax: Use new dax zero page method for zeroing a page

2020-04-03T02:15:03+00:00

Use new dax native zero page method for zeroing page if I/O is page
aligned. Otherwise fall back to direct_access() + memcpy().

This gets rid of one of the depenendency on block device in dax path.

Signed-off-by: Vivek Goyal 
Link: https://lore.kernel.org/r/20200228163456.1587-6-vgoyal@redhat.com
Signed-off-by: Dan Williams