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From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: "David Hildenbrand" <david@redhat.com>,
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Subject: [PATCH v1 7/7] fs: update documentation of get_write_access() and friends
Date: Thu, 12 Aug 2021 10:43:48 +0200	[thread overview]
Message-ID: <20210812084348.6521-8-david@redhat.com> (raw)
In-Reply-To: <20210812084348.6521-1-david@redhat.com>

As VM_DENYWRITE does no longer exists, let's spring-clean the
documentation of get_write_access() and friends.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 include/linux/fs.h | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 640574294216..e0dc3e96ed72 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3055,15 +3055,20 @@ static inline void file_end_write(struct file *file)
 }
 
 /*
+ * This is used for regular files where some users -- especially the
+ * currently executed binary in a process, previously handled via
+ * VM_DENYWRITE -- cannot handle concurrent write (and maybe mmap
+ * read-write shared) accesses.
+ *
  * get_write_access() gets write permission for a file.
  * put_write_access() releases this write permission.
- * This is used for regular files.
- * We cannot support write (and maybe mmap read-write shared) accesses and
- * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
- * can have the following values:
- * 0: no writers, no VM_DENYWRITE mappings
- * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
- * > 0: (i_writecount) users are writing to the file.
+ * deny_write_access() denies write access to a file.
+ * allow_write_access() re-enables write access to a file.
+ *
+ * The i_writecount field of an inode can have the following values:
+ * 0: no write access, no denied write access
+ * < 0: (-i_writecount) users that denied write access to the file.
+ * > 0: (i_writecount) users that have write access to the file.
  *
  * Normally we operate on that counter with atomic_{inc,dec} and it's safe
  * except for the cases where we don't hold i_writecount yet. Then we need to
-- 
2.31.1


  parent reply	other threads:[~2021-08-12  8:46 UTC|newest]

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-12  8:43 [PATCH v1 0/7] Remove in-tree usage of MAP_DENYWRITE David Hildenbrand
2021-08-12  8:43 ` [PATCH v1 1/7] binfmt: don't use MAP_DENYWRITE when loading shared libraries via uselib() David Hildenbrand
2021-08-12  8:43 ` [PATCH v1 2/7] kernel/fork: factor out atomcially replacing the current MM exe_file David Hildenbrand
2021-08-12  9:17   ` Christian Brauner
2021-08-12  8:43 ` [PATCH v1 3/7] kernel/fork: always deny write access to " David Hildenbrand
2021-08-12 10:05   ` Christian Brauner
2021-08-12 10:13     ` David Hildenbrand
2021-08-12 12:32       ` Christian Brauner
2021-08-12 12:38         ` David Hildenbrand
2021-08-12 16:51   ` Linus Torvalds
2021-08-12 19:38     ` David Hildenbrand
2021-08-12  8:43 ` [PATCH v1 4/7] binfmt: remove in-tree usage of MAP_DENYWRITE David Hildenbrand
2021-08-12  8:43 ` [PATCH v1 5/7] mm: remove VM_DENYWRITE David Hildenbrand
2021-08-12  8:43 ` [PATCH v1 6/7] mm: ignore MAP_DENYWRITE in ksys_mmap_pgoff() David Hildenbrand
2021-08-12  8:43 ` David Hildenbrand [this message]
2021-08-12 12:20 ` [PATCH v1 0/7] Remove in-tree usage of MAP_DENYWRITE Florian Weimer
2021-08-12 12:47   ` David Hildenbrand
2021-08-12 16:17   ` Eric W. Biederman
2021-08-12 17:32 ` Eric W. Biederman
2021-08-12 17:35   ` Andy Lutomirski
2021-08-12 17:48     ` Eric W. Biederman
2021-08-12 18:01       ` Andy Lutomirski
2021-08-12 18:10       ` Linus Torvalds
2021-08-12 18:47         ` Eric W. Biederman
2021-08-13  9:05           ` David Laight
2021-08-13 20:17             ` Eric W. Biederman
2021-08-13 20:51               ` Florian Weimer
2021-08-14  0:31               ` Linus Torvalds
2021-08-14  0:49                 ` Andy Lutomirski
2021-08-14  0:54                   ` Linus Torvalds
2021-08-14  0:58                     ` Linus Torvalds
2021-08-14  1:57                       ` Al Viro
2021-08-14  2:02                         ` Al Viro
2021-08-14  9:06                           ` David Hildenbrand
2021-08-14  7:53                         ` Christian Brauner
2021-08-14 19:52                     ` David Laight
2021-08-26 17:48                     ` Andy Lutomirski
2021-08-26 21:47                       ` David Hildenbrand
2021-08-26 22:13                         ` Eric W. Biederman
2021-08-27  8:22                           ` David Laight
2021-08-27 15:58                             ` Eric W. Biederman
2021-09-01  8:28                           ` David Hildenbrand
2021-08-27 10:18                         ` Christian Brauner
2021-08-14  3:04                   ` Matthew Wilcox
2021-08-17 16:48                     ` Removing Mandatory Locks Eric W. Biederman
2021-08-17 16:50                       ` David Hildenbrand
2021-08-18  9:34                       ` Rodrigo Campos
2021-08-19 19:18                         ` Jeff Layton
2021-08-19 20:03                           ` Willy Tarreau
2021-08-19 18:39                       ` Jeff Layton
2021-08-19 19:15                         ` Linus Torvalds
2021-08-19 19:55                           ` Eric Biggers
2021-08-19 20:18                           ` Jeff Layton
2021-08-19 20:31                             ` Linus Torvalds
2021-08-19 21:43                               ` Jeff Layton
2021-08-19 22:32                                 ` Linus Torvalds
2021-08-20  8:30                                   ` David Laight
2021-08-23  7:55                                     ` Geert Uytterhoeven
2021-08-23  8:14                                       ` David Laight
2021-08-20 13:43                                   ` Steven Rostedt
2021-08-20 16:06                                     ` Linus Torvalds
2021-08-20  2:10                               ` Matthew Wilcox
2021-08-20  6:36                               ` Amir Goldstein
2021-08-20  7:14                                 ` Amir Goldstein
2021-08-20 12:27                                   ` Jeff Layton
2021-08-20 12:38                                     ` Willy Tarreau
2021-08-20 13:03                                       ` Jeff Layton
2021-08-20 13:11                                         ` Willy Tarreau
2021-08-20 16:30                           ` Kees Cook
2021-08-20 19:17                             ` H. Peter Anvin
2021-08-20 21:29                               ` Jeff Layton
2021-08-20 21:29                                 ` Jeff Layton
2021-08-21 12:45                                 ` Jeff Layton
2021-08-21 12:45                                   ` Jeff Layton
2021-08-23 22:15                                   ` J. Bruce Fields
2021-08-20 22:31                               ` Matthew Wilcox
2021-08-18  7:51                     ` [PATCH v1 0/7] Remove in-tree usage of MAP_DENYWRITE Christian Brauner
2021-08-18 15:42                   ` J. Bruce Fields
2021-08-19 13:56                     ` Eric W. Biederman
2021-08-19 14:33                       ` J. Bruce Fields
2021-08-20 12:54                         ` Jeff Layton
2021-08-20  3:44                     ` NeilBrown
2021-08-20  8:25                       ` David Laight
2021-08-12 19:24         ` David Hildenbrand
2021-08-12 18:15       ` Florian Weimer
2021-08-12 18:21         ` Linus Torvalds

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