access_process_vm device memory infrastructure

[pandora-kernel.git] / Documentation / filesystems / Locking

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index f0f8258..680fb56 100644 (file)
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -90,10 +90,8 @@ of the locking scheme for directory operations.
 prototypes:
        struct inode *(*alloc_inode)(struct super_block *sb);
        void (*destroy_inode)(struct inode *);
-       void (*read_inode) (struct inode *);
        void (*dirty_inode) (struct inode *);
        int (*write_inode) (struct inode *, int);
-       void (*put_inode) (struct inode *);
        void (*drop_inode) (struct inode *);
        void (*delete_inode) (struct inode *);
        void (*put_super) (struct super_block *);
@@ -114,10 +112,8 @@ locking rules:
                        BKL     s_lock  s_umount
 alloc_inode:           no      no      no
 destroy_inode:         no
-read_inode:            no                              (see below)
 dirty_inode:           no                              (must not sleep)
 write_inode:           no
-put_inode:             no
 drop_inode:            no                              !!!inode_lock!!!
 delete_inode:          no
 put_super:             yes     yes     no
@@ -133,7 +129,6 @@ show_options:               no                              (vfsmount->sem)
 quota_read:            no      no      no              (see below)
 quota_write:           no      no      no              (see below)
 
-->read_inode() is not a method - it's a callback used in iget().
 ->remount_fs() will have the s_umount lock if it's already mounted.
 When called from get_sb_single, it does NOT have the s_umount lock.
 ->quota_read() and ->quota_write() functions are both guaranteed to
@@ -178,15 +173,18 @@ prototypes:
 locking rules:
        All except set_page_dirty may block
 
-                       BKL     PageLocked(page)
+                       BKL     PageLocked(page)        i_sem
 writepage:             no      yes, unlocks (see below)
 readpage:              no      yes, unlocks
 sync_page:             no      maybe
 writepages:            no
 set_page_dirty         no      no
 readpages:             no
-prepare_write:         no      yes
-commit_write:          no      yes
+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
 bmap:                  yes
 invalidatepage:                no      yes
 releasepage:           no      yes
@@ -221,7 +219,7 @@ against the page the filesystem should redirty the page with
 redirty_page_for_writepage(), then unlock the page and return zero.
 This may also be done to avoid internal deadlocks, but rarely.
 
-If the filesytem is called for sync then it must wait on any
+If the filesystem is called for sync then it must wait on any
 in-progress I/O and then start new I/O.
 
 The filesystem should unlock the page synchronously, before returning to the
@@ -511,16 +509,16 @@ prototypes:
        void (*open)(struct vm_area_struct*);
        void (*close)(struct vm_area_struct*);
        int (*fault)(struct vm_area_struct*, struct vm_fault *);
-       struct page *(*nopage)(struct vm_area_struct*, unsigned long, int *);
        int (*page_mkwrite)(struct vm_area_struct *, struct page *);
+       int (*access)(struct vm_area_struct *, unsigned long, void*, int, int);
 
 locking rules:
                BKL     mmap_sem        PageLocked(page)
 open:          no      yes
 close:         no      yes
 fault:         no      yes
-nopage:                no      yes
 page_mkwrite:  no      yes             no
+access:                no      yes
 
        ->page_mkwrite() is called when a previously read-only page is
 about to become writeable. The file system is responsible for
@@ -529,6 +527,11 @@ taking to lock out truncate, the page range should be verified to be
 within i_size. The page mapping should also be checked that it is not
 NULL.
 
+       ->access() is called when get_user_pages() fails in
+acces_process_vm(), typically used to debug a process through
+/proc/pid/mem or ptrace.  This function is needed only for
+VM_IO | VM_PFNMAP VMAs.
+
 ================================================================================
                        Dubious stuff
 
@@ -537,4 +540,3 @@ NULL.
 
 ipc/shm.c::shm_delete() - may need BKL.
 ->read() and ->write() in many drivers are (probably) missing BKL.
-drivers/sgi/char/graphics.c::sgi_graphics_nopage() - may need BKL.