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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 RFC 7/7] fs: update documentation of get_write_access() and friends
Date: Fri, 23 Apr 2021 15:16:40 +0200	[thread overview]
Message-ID: <20210423131640.20080-8-david@redhat.com> (raw)
In-Reply-To: <20210423131640.20080-1-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 ec8f3ddf4a6a..b0a410a14170 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2906,15 +2906,20 @@ 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
-- 
2.30.2


      parent reply	other threads:[~2021-04-23 13:19 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-23 13:16 [PATCH RFC 0/7] Remove in-tree usage of MAP_DENYWRITE David Hildenbrand
2021-04-23 13:16 ` [PATCH RFC 1/7] binfmt: don't use MAP_DENYWRITE when loading shared libraries via uselib() David Hildenbrand
2021-04-23 13:16 ` [PATCH RFC 2/7] kernel/fork: factor out atomcially replacing the current MM exe_file David Hildenbrand
2021-04-23 13:16 ` [PATCH RFC 3/7] kernel/fork: always deny write access to " David Hildenbrand
2021-04-23 13:16 ` [PATCH RFC 4/7] binfmt: remove in-tree usage of MAP_DENYWRITE David Hildenbrand
2021-04-23 13:16 ` [PATCH RFC 5/7] mm: remove VM_DENYWRITE David Hildenbrand
2021-04-23 13:16 ` [PATCH RFC 6/7] mm: ignore MAP_DENYWRITE in ksys_mmap_pgoff() David Hildenbrand
2021-04-23 13:16 ` David Hildenbrand [this message]

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