Merge branch 'for-2.6.28' of git://linux-nfs.org/~bfields/linux

[linux-2.6-omap-h63xx.git] / Documentation / filesystems / Locking

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 680fb566b9286bcc71a527c5f75d4b94fc9ac215..23d2f4460debf2122676e83a6d4c9139df889253 100644 (file)
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -144,8 +144,8 @@ prototypes:
        void (*kill_sb) (struct super_block *);
 locking rules:
                may block       BKL
-get_sb         yes             yes
-kill_sb                yes             yes
+get_sb         yes             no
+kill_sb                yes             no
 
 ->get_sb() returns error or 0 with locked superblock attached to the vfsmount
 (exclusive on ->s_umount).
@@ -161,8 +161,12 @@ prototypes:
        int (*set_page_dirty)(struct page *page);
        int (*readpages)(struct file *filp, struct address_space *mapping,
                        struct list_head *pages, unsigned nr_pages);
-       int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
-       int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
+       int (*write_begin)(struct file *, struct address_space *mapping,
+                               loff_t pos, unsigned len, unsigned flags,
+                               struct page **pagep, void **fsdata);
+       int (*write_end)(struct file *, struct address_space *mapping,
+                               loff_t pos, unsigned len, unsigned copied,
+                               struct page *page, void *fsdata);
        sector_t (*bmap)(struct address_space *, sector_t);
        int (*invalidatepage) (struct page *, unsigned long);
        int (*releasepage) (struct page *, int);
@@ -180,8 +184,6 @@ sync_page:          no      maybe
 writepages:            no
 set_page_dirty         no      no
 readpages:             no
-prepare_write:         no      yes                     yes
-commit_write:          no      yes                     yes
 write_begin:           no      locks the page          yes
 write_end:             no      yes, unlocks            yes
 perform_write:         no      n/a                     yes
@@ -191,7 +193,7 @@ releasepage:                no      yes
 direct_IO:             no
 launder_page:          no      yes
 
-       ->prepare_write(), ->commit_write(), ->sync_page() and ->readpage()
+       ->write_begin(), ->write_end(), ->sync_page() and ->readpage()
 may be called from the request handler (/dev/loop).
 
        ->readpage() unlocks the page, either synchronously or via I/O
@@ -409,12 +411,12 @@ ioctl:                    yes     (see below)
 unlocked_ioctl:                no      (see below)
 compat_ioctl:          no
 mmap:                  no
-open:                  maybe   (see below)
+open:                  no
 flush:                 no
 release:               no
 fsync:                 no      (see below)
 aio_fsync:             no
-fasync:                        yes     (see below)
+fasync:                        no
 lock:                  yes
 readv:                 no
 writev:                        no
@@ -431,13 +433,6 @@ For many filesystems, it is probably safe to acquire the inode
 semaphore.  Note some filesystems (i.e. remote ones) provide no
 protection for i_size so you will need to use the BKL.
 
-->open() locking is in-transit: big lock partially moved into the methods.
-The only exception is ->open() in the instances of file_operations that never
-end up in ->i_fop/->proc_fops, i.e. ones that belong to character devices
-(chrdev_open() takes lock before replacing ->f_op and calling the secondary
-method. As soon as we fix the handling of module reference counters all
-instances of ->open() will be called without the BKL.
-
 Note: ext2_release() was *the* source of contention on fs-intensive
 loads and dropping BKL on ->release() helps to get rid of that (we still
 grab BKL for cases when we close a file that had been opened r/w, but that