From: Alexander Viro <viro@math.psu.edu>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] Documentation/filesystems/Locking update
Date: Thu, 11 Jan 2001 01:13:10 -0500 (EST) [thread overview]
Message-ID: <Pine.GSO.4.21.0101110109440.15355-100000@weyl.math.psu.edu> (raw)
Patch updates filesystems/Locking - corrects ->writepage()
prototype, removes dead vma methods and corrects ->writepage() and
->readpage() description wrt page lock.
Please, apply.
diff -urN S1-pre1/Documentation/filesystems/Locking S1-pre1-s_lock/Documentation/filesystems/Locking
--- S1-pre1/Documentation/filesystems/Locking Fri Jul 28 15:50:51 2000
+++ S1-pre1-s_lock/Documentation/filesystems/Locking Thu Jan 11 01:01:14 2001
@@ -117,7 +117,7 @@
--------------------------- address_space_operations --------------------------
prototypes:
- int (*writepage)(struct file *, struct page *);
+ int (*writepage)(struct page *);
int (*readpage)(struct file *, struct page *);
int (*sync_page)(struct page *);
int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
@@ -126,8 +126,8 @@
locking rules:
All may block
BKL PageLocked(page)
-writepage: no yes
-readpage: no yes
+writepage: no yes, unlocks
+readpage: no yes, unlocks
sync_page: no maybe
prepare_write: no yes
commit_write: no yes
@@ -135,6 +135,7 @@
->prepare_write(), ->commit_write(), ->sync_page() and ->readpage()
may be called from the request handler (/dev/loop).
+ ->readpage() and ->writepage() unlock the page.
->sync_page() locking rules are not well-defined - usually it is called
with lock on page, but that is not guaranteed. Considering the currently
existing instances of this method ->sync_page() itself doesn't look
@@ -285,26 +286,13 @@
prototypes:
void (*open)(struct vm_area_struct*);
void (*close)(struct vm_area_struct*);
- void (*unmap)(struct vm_area_struct*, unsigned long, size_t);
- void (*protect)(struct vm_area_struct*, unsigned long, size_t, unsigned);
- int (*sync)(struct vm_area_struct*, unsigned long, size_t, unsigned);
struct page *(*nopage)(struct vm_area_struct*, unsigned long, int);
- struct page *(*wppage)(struct vm_area_struct*, unsigned long, struct page*);
- int (*swapout)(struct page *, struct file *);
locking rules:
BKL mmap_sem
open: no yes
close: no yes
-sync: no yes
-unmap: no yes
nopage: no yes
-swapout: yes yes
-wpppage: (see below)
-protect: (see below)
-
-->wppage() and ->protect() have no instances and nothing calls them; looks like
-they must die...
================================================================================
Dubious stuff
-
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