linux/fs/ocfs2
Arnd Bergmann 6038f373a3 llseek: automatically add .llseek fop
All file_operations should get a .llseek operation so we can make
nonseekable_open the default for future file operations without a
.llseek pointer.

The three cases that we can automatically detect are no_llseek, seq_lseek
and default_llseek. For cases where we can we can automatically prove that
the file offset is always ignored, we use noop_llseek, which maintains
the current behavior of not returning an error from a seek.

New drivers should normally not use noop_llseek but instead use no_llseek
and call nonseekable_open at open time.  Existing drivers can be converted
to do the same when the maintainer knows for certain that no user code
relies on calling seek on the device file.

The generated code is often incorrectly indented and right now contains
comments that clarify for each added line why a specific variant was
chosen. In the version that gets submitted upstream, the comments will
be gone and I will manually fix the indentation, because there does not
seem to be a way to do that using coccinelle.

Some amount of new code is currently sitting in linux-next that should get
the same modifications, which I will do at the end of the merge window.

Many thanks to Julia Lawall for helping me learn to write a semantic
patch that does all this.

===== begin semantic patch =====
// This adds an llseek= method to all file operations,
// as a preparation for making no_llseek the default.
//
// The rules are
// - use no_llseek explicitly if we do nonseekable_open
// - use seq_lseek for sequential files
// - use default_llseek if we know we access f_pos
// - use noop_llseek if we know we don't access f_pos,
//   but we still want to allow users to call lseek
//
@ open1 exists @
identifier nested_open;
@@
nested_open(...)
{
<+...
nonseekable_open(...)
...+>
}

@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
<+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+>
}

@ read disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
<+...
(
   *off = E
|
   *off += E
|
   func(..., off, ...)
|
   E = *off
)
...+>
}

@ read_no_fpos disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
... when != off
}

@ write @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
<+...
(
  *off = E
|
  *off += E
|
  func(..., off, ...)
|
  E = *off
)
...+>
}

@ write_no_fpos @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
... when != off
}

@ fops0 @
identifier fops;
@@
struct file_operations fops = {
 ...
};

@ has_llseek depends on fops0 @
identifier fops0.fops;
identifier llseek_f;
@@
struct file_operations fops = {
...
 .llseek = llseek_f,
...
};

@ has_read depends on fops0 @
identifier fops0.fops;
identifier read_f;
@@
struct file_operations fops = {
...
 .read = read_f,
...
};

@ has_write depends on fops0 @
identifier fops0.fops;
identifier write_f;
@@
struct file_operations fops = {
...
 .write = write_f,
...
};

@ has_open depends on fops0 @
identifier fops0.fops;
identifier open_f;
@@
struct file_operations fops = {
...
 .open = open_f,
...
};

// use no_llseek if we call nonseekable_open
////////////////////////////////////////////
@ nonseekable1 depends on !has_llseek && has_open @
identifier fops0.fops;
identifier nso ~= "nonseekable_open";
@@
struct file_operations fops = {
...  .open = nso, ...
+.llseek = no_llseek, /* nonseekable */
};

@ nonseekable2 depends on !has_llseek @
identifier fops0.fops;
identifier open.open_f;
@@
struct file_operations fops = {
...  .open = open_f, ...
+.llseek = no_llseek, /* open uses nonseekable */
};

// use seq_lseek for sequential files
/////////////////////////////////////
@ seq depends on !has_llseek @
identifier fops0.fops;
identifier sr ~= "seq_read";
@@
struct file_operations fops = {
...  .read = sr, ...
+.llseek = seq_lseek, /* we have seq_read */
};

// use default_llseek if there is a readdir
///////////////////////////////////////////
@ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier readdir_e;
@@
// any other fop is used that changes pos
struct file_operations fops = {
... .readdir = readdir_e, ...
+.llseek = default_llseek, /* readdir is present */
};

// use default_llseek if at least one of read/write touches f_pos
/////////////////////////////////////////////////////////////////
@ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read.read_f;
@@
// read fops use offset
struct file_operations fops = {
... .read = read_f, ...
+.llseek = default_llseek, /* read accesses f_pos */
};

@ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write.write_f;
@@
// write fops use offset
struct file_operations fops = {
... .write = write_f, ...
+	.llseek = default_llseek, /* write accesses f_pos */
};

// Use noop_llseek if neither read nor write accesses f_pos
///////////////////////////////////////////////////////////

@ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
identifier write_no_fpos.write_f;
@@
// write fops use offset
struct file_operations fops = {
...
 .write = write_f,
 .read = read_f,
...
+.llseek = noop_llseek, /* read and write both use no f_pos */
};

@ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write_no_fpos.write_f;
@@
struct file_operations fops = {
... .write = write_f, ...
+.llseek = noop_llseek, /* write uses no f_pos */
};

@ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
@@
struct file_operations fops = {
... .read = read_f, ...
+.llseek = noop_llseek, /* read uses no f_pos */
};

@ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Julia Lawall <julia@diku.dk>
Cc: Christoph Hellwig <hch@infradead.org>
2010-10-15 15:53:27 +02:00
..
cluster O2net: Disallow o2net accept connection request from itself. 2010-08-07 10:50:33 -07:00
dlm Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2 2010-08-13 10:43:50 -07:00
dlmfs llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
acl.c Fix the nested PR lock calling issue in ACL 2010-08-07 10:46:46 -07:00
acl.h ocfs2: Always include ACL support 2009-10-28 23:05:57 -07:00
alloc.c ocfs2: Fix deadlock when allocating page 2010-09-08 14:25:57 +08:00
alloc.h Merge branch 'discontig-bg' of git://oss.oracle.com/git/tma/linux-2.6 into ocfs2-merge-window 2010-05-18 16:40:42 -07:00
aops.c sort out blockdev_direct_IO variants 2010-08-09 16:47:29 -04:00
aops.h ocfs2: Add CoW support. 2009-09-22 20:09:36 -07:00
blockcheck.c ocfs2: Fix metaecc error messages 2010-09-08 14:25:53 +08:00
blockcheck.h ocfs2: Add statistics for the checksum and ecc operations. 2009-06-03 19:15:36 -07:00
buffer_head_io.c Merge branch 'skip_delete_inode' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2-mark into ocfs2-fixes 2010-04-30 13:37:29 -07:00
buffer_head_io.h ocfs2: Take the inode out of the metadata read/write paths. 2009-09-04 16:07:48 -07:00
dcache.c ocfs2: invalidate dentry if its dentry_lock isn't initialized. 2009-08-27 18:10:54 -07:00
dcache.h ocfs2: Fix deadlock on umount 2009-07-21 15:47:55 -07:00
dir.c Merge branch 'discontig-bg' of git://oss.oracle.com/git/tma/linux-2.6 into ocfs2-merge-window 2010-05-18 16:40:42 -07:00
dir.h ocfs2: Introduce dir free space list 2009-04-03 11:39:16 -07:00
dlmglue.c fs/ocfs2: Remove unnecessary casts of private_data 2010-07-20 17:20:08 +02:00
dlmglue.h ocfs2: Add new refcount tree lock resource in dlmglue. 2009-09-22 20:09:28 -07:00
export.c ocfs2/trivial: Remove trailing whitespaces 2010-01-25 19:20:51 -08:00
export.h
extent_map.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
extent_map.h ocfs2: Return extent flags for xattr value tree. 2009-09-22 20:09:39 -07:00
file.c Ocfs2: Fix a regression bug from mainline commit(6b933c8e6f). 2010-09-08 14:25:57 +08:00
file.h ocfs2: Zero the tail cluster when extending past i_size. 2010-07-08 13:25:35 -07:00
heartbeat.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
heartbeat.h
inode.c ocfs2: Fix incorrect checksum validation error 2010-09-08 14:25:54 +08:00
inode.h Make ->drop_inode() just return whether inode needs to be dropped 2010-08-09 16:48:35 -04:00
ioctl.c ocfs2: Use compat_ptr in reflink_arguments. 2010-02-02 18:56:37 -08:00
ioctl.h Ocfs2: Move ocfs2 ioctl definitions from ocfs2_fs.h to newly added ocfs2_ioctl.h 2010-03-02 14:10:20 -08:00
journal.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2010-08-07 13:03:53 -07:00
journal.h ocfs2: Make ocfs2_journal_dirty() void. 2010-05-05 18:17:29 -07:00
Kconfig ocfs2: Always include ACL support 2009-10-28 23:05:57 -07:00
localalloc.c ocfs2: Limit default local alloc size within bitmap range. 2010-06-15 16:50:43 -07:00
localalloc.h ocfs2: increase the default size of local alloc windows 2010-05-05 18:18:07 -07:00
locks.c [PATCH] Skip check for mandatory locks when unlocking 2010-03-17 12:07:16 -07:00
locks.h
Makefile ocfs2: allocation reservations 2010-05-05 18:17:30 -07:00
mmap.c ocfs2: make __ocfs2_page_mkwrite handle file end properly. 2010-09-08 14:25:55 +08:00
mmap.h
namei.c ocfs2: Fix orphan add in ocfs2_create_inode_in_orphan 2010-09-08 14:26:00 +08:00
namei.h ocfs2: Create reflinked file in orphan dir. 2009-09-22 20:09:48 -07:00
ocfs1_fs_compat.h
ocfs2_fs.h ocfs2: increase the default size of local alloc windows 2010-05-05 18:18:07 -07:00
ocfs2_ioctl.h Ocfs2: Move ocfs2 ioctl definitions from ocfs2_fs.h to newly added ocfs2_ioctl.h 2010-03-02 14:10:20 -08:00
ocfs2_lockid.h ocfs2: Add new refcount tree lock resource in dlmglue. 2009-09-22 20:09:28 -07:00
ocfs2_lockingver.h ocfs2_dlmfs: Enable the use of user cluster stacks. 2010-02-26 15:41:18 -08:00
ocfs2.h ocfs2: Add dir_resv_level mount option 2010-05-05 18:18:07 -07:00
quota_global.c ocfs2: Zero the tail cluster when extending past i_size. 2010-07-08 13:25:35 -07:00
quota_local.c ocfs2: Zero the tail cluster when extending past i_size. 2010-07-08 13:25:35 -07:00
quota.h ocfs2: Fix NULL pointer deref when writing local dquot 2010-05-21 19:30:48 +02:00
refcounttree.c ocfs2: Fix deadlock when allocating page 2010-09-08 14:25:57 +08:00
refcounttree.h Ocfs2: Optimize ocfs2 truncate to use ocfs2_remove_btree_range() instead. 2010-05-18 12:25:10 -07:00
reservations.c ocfs2: update gfp/slab.h includes 2010-06-28 10:19:19 +10:00
reservations.h ocfs2: make ocfs2_adjust_resv_from_alloc simple. 2010-05-05 18:18:09 -07:00
resize.c ocfs2: Make ocfs2_journal_dirty() void. 2010-05-05 18:17:29 -07:00
resize.h
slot_map.c ocfs2: Take the inode out of the metadata read/write paths. 2009-09-04 16:07:48 -07:00
slot_map.h
stack_o2cb.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
stack_user.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
stackglue.c ocfs2_dlmfs: Enable the use of user cluster stacks. 2010-02-26 15:41:18 -08:00
stackglue.h ocfs2_dlmfs: Enable the use of user cluster stacks. 2010-02-26 15:41:18 -08:00
suballoc.c ocfs2: allow return of new inode block location before allocation of the inode 2010-09-08 14:25:59 +08:00
suballoc.h ocfs2: allow return of new inode block location before allocation of the inode 2010-09-08 14:25:59 +08:00
super.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2010-08-10 11:26:52 -07:00
super.h ocfs2: Wrap signal blocking in void functions. 2010-05-10 11:50:10 -07:00
symlink.c ocfs2: Fix refcnt leak on ocfs2_fast_follow_link() error path 2010-01-11 15:38:50 -08:00
symlink.h
sysfile.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
sysfile.h
uptodate.c ocfs2/trivial: Remove trailing whitespaces 2010-01-25 19:20:51 -08:00
uptodate.h ocfs2: Pass struct ocfs2_caching_info to the journal functions. 2009-09-04 16:07:50 -07:00
ver.c
ver.h
xattr.c ocfs2: Make xattr reflink work with new local alloc reservation. 2010-07-12 13:57:50 -07:00
xattr.h ocfs: constify xattr_handler 2010-05-21 18:31:20 -04:00