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 *);
void (*write_super) (struct super_block *);
int (*sync_fs)(struct super_block *sb, int wait);
- void (*write_super_lockfs) (struct super_block *);
- void (*unlockfs) (struct super_block *);
+ int (*freeze_fs) (struct super_block *);
+ int (*unfreeze_fs) (struct super_block *);
int (*statfs) (struct dentry *, struct kstatfs *);
int (*remount_fs) (struct super_block *, int *, char *);
void (*clear_inode) (struct inode *);
locking rules:
All may block.
- 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
-write_super: no yes read
-sync_fs: no no read
-write_super_lockfs: ?
-unlockfs: ?
-statfs: no no no
-remount_fs: yes yes maybe (see below)
-clear_inode: no
-umount_begin: yes no no
-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.
+ None have BKL
+ s_umount
+alloc_inode:
+destroy_inode:
+dirty_inode: (must not sleep)
+write_inode:
+drop_inode: !!!inode_lock!!!
+delete_inode:
+put_super: write
+write_super: read
+sync_fs: read
+freeze_fs: read
+unfreeze_fs: read
+statfs: no
+remount_fs: maybe (see below)
+clear_inode:
+umount_begin: no
+show_options: no (namespace_sem)
+quota_read: no (see below)
+quota_write: no (see below)
+
+->remount_fs() will have the s_umount exclusive 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
be the only ones operating on the quota file by the quota code (via
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).
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);
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
-bmap: yes
+write_begin: no locks the page yes
+write_end: no yes, unlocks yes
+perform_write: no n/a yes
+bmap: no
invalidatepage: no yes
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
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
unsigned long (*get_unmapped_area)(struct file *, unsigned long,
unsigned long, unsigned long, unsigned long);
int (*check_flags)(int);
- int (*dir_notify)(struct file *, unsigned long);
};
locking rules:
- All except ->poll() may block.
+ All may block.
BKL
llseek: no (see below)
read: no
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
sendpage: no
get_unmapped_area: no
check_flags: no
-dir_notify: no
->llseek() locking has moved from llseek to the individual llseek
implementations. If your fs is not using generic_file_llseek, you
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
can and should be done using the internal locking with smaller critical areas).
Current worst offender is ext2_get_block()...
-->fasync() is a mess. This area needs a big cleanup and that will probably
-affect locking.
+->fasync() is called without BKL protection, and is responsible for
+maintaining the FASYNC bit in filp->f_flags. Most instances call
+fasync_helper(), which does that maintenance, so it's not normally
+something one needs to worry about. Return values > 0 will be mapped to
+zero in the VFS layer.
->readdir() and ->ioctl() on directories must be changed. Ideally we would
move ->readdir() to inode_operations and use a separate method for directory
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 (*page_mkwrite)(struct vm_area_struct *, struct vm_fault *);
+ 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
-
- ->page_mkwrite() is called when a previously read-only page is
-about to become writeable. The file system is responsible for
-protecting against truncate races. Once appropriate action has been
-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.
+fault: no yes can return with page locked
+page_mkwrite: no yes can return with page locked
+access: no yes
+
+ ->fault() is called when a previously not present pte is about
+to be faulted in. The filesystem must find and return the page associated
+with the passed in "pgoff" in the vm_fault structure. If it is possible that
+the page may be truncated and/or invalidated, then the filesystem must lock
+the page, then ensure it is not already truncated (the page lock will block
+subsequent truncate), and then return with VM_FAULT_LOCKED, and the page
+locked. The VM will unlock the page.
+
+ ->page_mkwrite() is called when a previously read-only pte is
+about to become writeable. The filesystem again must ensure that there are
+no truncate/invalidate races, and then return with the page locked. If
+the page has been truncated, the filesystem should not look up a new page
+like the ->fault() handler, but simply return with VM_FAULT_NOPAGE, which
+will cause the VM to retry the fault.
+
+ ->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
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.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff