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* return an ERR_PTR from __filemap_get_folio v2
@ 2023-01-21  6:57 ` Christoph Hellwig
  0 siblings, 0 replies; 55+ messages in thread
From: Christoph Hellwig @ 2023-01-21  6:57 UTC (permalink / raw)
  To: Andrew Morton, Matthew Wilcox, Hugh Dickins
  Cc: linux-afs, linux-btrfs, linux-ext4, cluster-devel, linux-mm,
	linux-xfs, linux-fsdevel, linux-nilfs

Hi all,

__filemap_get_folio and its wrappers can return NULL for three different
conditions, which in some cases requires the caller to reverse engineer
the decision making.  This is fixed by returning an ERR_PTR instead of
NULL and thus transporting the reason for the failure.  But to make
that work we first need to ensure that no xa_value special case is
returned and thus return the FGP_ENTRY flag.  It turns out that flag
is barely used and can usually be deal with in a better way.

Note that the shmem patches in here are non-trivial and need some
careful review and testing.

Changes since v1:
 - drop the patches to check for errors in btrfs and gfs2
 - document the new calling conventions for the wrappers around
   __filemap_get_folio
 - rebased against the iomap changes in latest linux-next

Diffstat
 fs/afs/dir.c             |   10 +++----
 fs/afs/dir_edit.c        |    2 -
 fs/afs/write.c           |    4 +-
 fs/btrfs/disk-io.c       |    2 -
 fs/ext4/inode.c          |    2 -
 fs/ext4/move_extent.c    |    8 ++---
 fs/hugetlbfs/inode.c     |    2 -
 fs/iomap/buffered-io.c   |   15 +----------
 fs/netfs/buffered_read.c |    4 +-
 fs/nilfs2/page.c         |    6 ++--
 include/linux/pagemap.h  |   15 +++++------
 include/linux/shmem_fs.h |    1 
 mm/filemap.c             |   27 ++++++++-----------
 mm/folio-compat.c        |    4 +-
 mm/huge_memory.c         |    5 +--
 mm/memcontrol.c          |    2 -
 mm/mincore.c             |    2 -
 mm/shmem.c               |   64 +++++++++++++++++++----------------------------
 mm/swap_state.c          |   17 ++++++------
 mm/swapfile.c            |    4 +-
 mm/truncate.c            |   15 +++++------
 21 files changed, 94 insertions(+), 117 deletions(-)

^ permalink raw reply	[flat|nested] 55+ messages in thread
* return an ERR_PTR from __filemap_get_folio v3
@ 2023-03-07 14:34 Christoph Hellwig
  2023-03-07 14:34   ` Christoph Hellwig
  0 siblings, 1 reply; 55+ messages in thread
From: Christoph Hellwig @ 2023-03-07 14:34 UTC (permalink / raw)
  To: Andrew Morton, Matthew Wilcox, Hugh Dickins
  Cc: linux-afs, linux-btrfs, linux-ext4, cluster-devel, linux-mm,
	linux-xfs, linux-fsdevel, linux-nilfs

Hi all,

__filemap_get_folio and its wrappers can return NULL for three different
conditions, which in some cases requires the caller to reverse engineer
the decision making.  This is fixed by returning an ERR_PTR instead of
NULL and thus transporting the reason for the failure.  But to make
that work we first need to ensure that no xa_value special case is
returned and thus return the FGP_ENTRY flag.  It turns out that flag
is barely used and can usually be deal with in a better way.

Note that the shmem patches in here are non-trivial and I would appreicate
a careful review from Hugh.

Changes since v2:
 - rebased to v6.3-rc which includes a couple of new callsites

Changes since v1:
 - drop the patches to check for errors in btrfs and gfs2
 - document the new calling conventions for the wrappers around
   __filemap_get_folio
 - rebased against the iomap changes in latest linux-next

Diffstat
 fs/afs/dir.c             |   10 +++----
 fs/afs/dir_edit.c        |    2 -
 fs/afs/write.c           |    4 +-
 fs/ext4/inode.c          |    2 -
 fs/ext4/move_extent.c    |    8 ++---
 fs/hugetlbfs/inode.c     |    2 -
 fs/iomap/buffered-io.c   |   11 +-------
 fs/netfs/buffered_read.c |    4 +-
 fs/nfs/file.c            |    4 +-
 fs/nilfs2/page.c         |    6 ++--
 include/linux/pagemap.h  |   15 +++++------
 include/linux/shmem_fs.h |    1 
 mm/filemap.c             |   27 ++++++++-----------
 mm/folio-compat.c        |    4 +-
 mm/huge_memory.c         |    5 +--
 mm/hugetlb.c             |    6 ++--
 mm/memcontrol.c          |    2 -
 mm/mincore.c             |    2 -
 mm/shmem.c               |   64 +++++++++++++++++++----------------------------
 mm/swap_state.c          |   17 ++++++------
 mm/swapfile.c            |    4 +-
 mm/truncate.c            |   15 +++++------
 22 files changed, 99 insertions(+), 116 deletions(-)

^ permalink raw reply	[flat|nested] 55+ messages in thread

end of thread, other threads:[~2023-03-29 23:56 UTC | newest]

Thread overview: 55+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-01-21  6:57 return an ERR_PTR from __filemap_get_folio v2 Christoph Hellwig
2023-01-21  6:57 ` Christoph Hellwig
2023-01-21  6:57 ` [Cluster-devel] " Christoph Hellwig
2023-01-21  6:57 ` [PATCH 1/7] mm: don't look at xarray value entries in split_huge_pages_in_file Christoph Hellwig
2023-01-21  6:57   ` [Cluster-devel] " Christoph Hellwig
2023-01-21  6:57 ` [PATCH 2/7] mm: make mapping_get_entry available outside of filemap.c Christoph Hellwig
2023-01-21  6:57   ` [Cluster-devel] " Christoph Hellwig
2023-01-21  6:57 ` [PATCH 3/7] mm: use filemap_get_entry in filemap_get_incore_folio Christoph Hellwig
2023-01-21  6:57   ` Christoph Hellwig
2023-01-21  6:57   ` [Cluster-devel] " Christoph Hellwig
2023-01-21  6:57 ` [PATCH 4/7] shmem: remove shmem_get_partial_folio Christoph Hellwig
2023-01-21  6:57   ` [Cluster-devel] " Christoph Hellwig
2023-01-21  6:57 ` [PATCH 5/7] shmem: open code the page cache lookup in shmem_get_folio_gfp Christoph Hellwig
2023-01-21  6:57   ` Christoph Hellwig
2023-01-21  6:57   ` [Cluster-devel] " Christoph Hellwig
2023-01-21  6:57 ` [PATCH 6/7] mm: remove FGP_ENTRY Christoph Hellwig
2023-01-21  6:57   ` [Cluster-devel] " Christoph Hellwig
2023-01-21  6:57 ` [PATCH 7/7] mm: return an ERR_PTR from __filemap_get_folio Christoph Hellwig
2023-01-21  6:57   ` [Cluster-devel] " Christoph Hellwig
2023-01-21 11:52   ` kernel test robot
2023-01-21 11:52     ` kernel test robot
2023-01-21 11:52     ` [Cluster-devel] " kernel test robot
2023-01-21 14:28     ` Christoph Hellwig
2023-01-21 14:28       ` [Cluster-devel] " Christoph Hellwig
2023-01-23 15:44   ` David Sterba
2023-01-23 15:44     ` [Cluster-devel] " David Sterba
2023-01-26 17:24   ` Ryusuke Konishi
2023-01-26 17:24     ` Ryusuke Konishi
2023-01-26 17:24     ` [Cluster-devel] " Ryusuke Konishi
2023-03-10  4:31   ` Naoya Horiguchi
2023-03-10  4:31     ` [Cluster-devel] " Naoya Horiguchi
2023-03-10  7:00     ` Christoph Hellwig
2023-03-10  7:00       ` Christoph Hellwig
2023-03-10  7:00       ` [Cluster-devel] " Christoph Hellwig
2023-03-10  8:02       ` Naoya Horiguchi
2023-03-10  8:02         ` [Cluster-devel] " Naoya Horiguchi
2023-01-22  1:06 ` return an ERR_PTR from __filemap_get_folio v2 Andrew Morton
2023-01-22  1:06   ` Andrew Morton
2023-01-22  1:06   ` [Cluster-devel] " Andrew Morton
2023-01-22  7:20   ` Christoph Hellwig
2023-01-22  7:20     ` Christoph Hellwig
2023-01-22  7:20     ` [Cluster-devel] " Christoph Hellwig
2023-01-23 18:59     ` Andrew Morton
2023-01-23 18:59       ` Andrew Morton
2023-01-23 18:59       ` [Cluster-devel] " Andrew Morton
2023-01-23 19:18       ` Christoph Hellwig
2023-01-23 19:18         ` Christoph Hellwig
2023-01-23 19:18         ` [Cluster-devel] " Christoph Hellwig
2023-03-28 23:04 ` Andrew Morton
2023-03-28 23:04   ` [Cluster-devel] " Andrew Morton
2023-03-29 23:56   ` Christoph Hellwig
2023-03-29 23:56     ` Christoph Hellwig
2023-03-29 23:56     ` [Cluster-devel] " Christoph Hellwig
2023-03-07 14:34 return an ERR_PTR from __filemap_get_folio v3 Christoph Hellwig
2023-03-07 14:34 ` [PATCH 6/7] mm: remove FGP_ENTRY Christoph Hellwig
2023-03-07 14:34   ` Christoph Hellwig

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