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linux-2.6/drivers/scsi/osd/osd_uld.c
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

572 lines
14 KiB
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/*
* osd_uld.c - OSD Upper Layer Driver
*
* A Linux driver module that registers as a SCSI ULD and probes
* for OSD type SCSI devices.
* It's main function is to export osd devices to in-kernel users like
* osdfs and pNFS-objects-LD. It also provides one ioctl for running
* in Kernel tests.
*
* Copyright (C) 2008 Panasas Inc. All rights reserved.
*
* Authors:
* Boaz Harrosh <bharrosh@panasas.com>
* Benny Halevy <bhalevy@panasas.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Panasas company nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <linux/namei.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/idr.h>
#include <linux/major.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <scsi/scsi.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/osd_initiator.h>
#include <scsi/osd_sec.h>
#include "osd_debug.h"
#ifndef TYPE_OSD
# define TYPE_OSD 0x11
#endif
#ifndef SCSI_OSD_MAJOR
# define SCSI_OSD_MAJOR 260
#endif
#define SCSI_OSD_MAX_MINOR 64
static const char osd_name[] = "osd";
static const char *osd_version_string = "open-osd 0.2.0";
MODULE_AUTHOR("Boaz Harrosh <bharrosh@panasas.com>");
MODULE_DESCRIPTION("open-osd Upper-Layer-Driver osd.ko");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(SCSI_OSD_MAJOR);
MODULE_ALIAS_SCSI_DEVICE(TYPE_OSD);
struct osd_uld_device {
int minor;
struct device class_dev;
struct cdev cdev;
struct osd_dev od;
struct osd_dev_info odi;
struct gendisk *disk;
};
struct osd_dev_handle {
struct osd_dev od;
struct file *file;
struct osd_uld_device *oud;
} ;
static DEFINE_IDA(osd_minor_ida);
static struct class osd_uld_class = {
.owner = THIS_MODULE,
.name = "scsi_osd",
};
/*
* Char Device operations
*/
static int osd_uld_open(struct inode *inode, struct file *file)
{
struct osd_uld_device *oud = container_of(inode->i_cdev,
struct osd_uld_device, cdev);
get_device(&oud->class_dev);
/* cache osd_uld_device on file handle */
file->private_data = oud;
OSD_DEBUG("osd_uld_open %p\n", oud);
return 0;
}
static int osd_uld_release(struct inode *inode, struct file *file)
{
struct osd_uld_device *oud = file->private_data;
OSD_DEBUG("osd_uld_release %p\n", file->private_data);
file->private_data = NULL;
put_device(&oud->class_dev);
return 0;
}
/* FIXME: Only one vector for now */
unsigned g_test_ioctl;
do_test_fn *g_do_test;
int osduld_register_test(unsigned ioctl, do_test_fn *do_test)
{
if (g_test_ioctl)
return -EINVAL;
g_test_ioctl = ioctl;
g_do_test = do_test;
return 0;
}
EXPORT_SYMBOL(osduld_register_test);
void osduld_unregister_test(unsigned ioctl)
{
if (ioctl == g_test_ioctl) {
g_test_ioctl = 0;
g_do_test = NULL;
}
}
EXPORT_SYMBOL(osduld_unregister_test);
static do_test_fn *_find_ioctl(unsigned cmd)
{
if (g_test_ioctl == cmd)
return g_do_test;
else
return NULL;
}
static long osd_uld_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct osd_uld_device *oud = file->private_data;
int ret;
do_test_fn *do_test;
do_test = _find_ioctl(cmd);
if (do_test)
ret = do_test(&oud->od, cmd, arg);
else {
OSD_ERR("Unknown ioctl %d: osd_uld_device=%p\n", cmd, oud);
ret = -ENOIOCTLCMD;
}
return ret;
}
static const struct file_operations osd_fops = {
.owner = THIS_MODULE,
.open = osd_uld_open,
.release = osd_uld_release,
.unlocked_ioctl = osd_uld_ioctl,
.llseek = noop_llseek,
};
struct osd_dev *osduld_path_lookup(const char *name)
{
struct osd_uld_device *oud;
struct osd_dev_handle *odh;
struct file *file;
int error;
if (!name || !*name) {
OSD_ERR("Mount with !path || !*path\n");
return ERR_PTR(-EINVAL);
}
odh = kzalloc(sizeof(*odh), GFP_KERNEL);
if (unlikely(!odh))
return ERR_PTR(-ENOMEM);
file = filp_open(name, O_RDWR, 0);
if (IS_ERR(file)) {
error = PTR_ERR(file);
goto free_od;
}
if (file->f_op != &osd_fops){
error = -EINVAL;
goto close_file;
}
oud = file->private_data;
odh->od = oud->od;
odh->file = file;
odh->oud = oud;
return &odh->od;
close_file:
fput(file);
free_od:
kfree(odh);
return ERR_PTR(error);
}
EXPORT_SYMBOL(osduld_path_lookup);
static inline bool _the_same_or_null(const u8 *a1, unsigned a1_len,
const u8 *a2, unsigned a2_len)
{
if (!a2_len) /* User string is Empty means don't care */
return true;
if (a1_len != a2_len)
return false;
return 0 == memcmp(a1, a2, a1_len);
}
struct find_oud_t {
const struct osd_dev_info *odi;
struct device *dev;
struct osd_uld_device *oud;
} ;
int _mach_odi(struct device *dev, void *find_data)
{
struct osd_uld_device *oud = container_of(dev, struct osd_uld_device,
class_dev);
struct find_oud_t *fot = find_data;
const struct osd_dev_info *odi = fot->odi;
if (_the_same_or_null(oud->odi.systemid, oud->odi.systemid_len,
odi->systemid, odi->systemid_len) &&
_the_same_or_null(oud->odi.osdname, oud->odi.osdname_len,
odi->osdname, odi->osdname_len)) {
OSD_DEBUG("found device sysid_len=%d osdname=%d\n",
odi->systemid_len, odi->osdname_len);
fot->oud = oud;
return 1;
} else {
return 0;
}
}
/* osduld_info_lookup - Loop through all devices, return the requested osd_dev.
*
* if @odi->systemid_len and/or @odi->osdname_len are zero, they act as a don't
* care. .e.g if they're both zero /dev/osd0 is returned.
*/
struct osd_dev *osduld_info_lookup(const struct osd_dev_info *odi)
{
struct find_oud_t find = {.odi = odi};
find.dev = class_find_device(&osd_uld_class, NULL, &find, _mach_odi);
if (likely(find.dev)) {
struct osd_dev_handle *odh = kzalloc(sizeof(*odh), GFP_KERNEL);
if (unlikely(!odh)) {
put_device(find.dev);
return ERR_PTR(-ENOMEM);
}
odh->od = find.oud->od;
odh->oud = find.oud;
return &odh->od;
}
return ERR_PTR(-ENODEV);
}
EXPORT_SYMBOL(osduld_info_lookup);
void osduld_put_device(struct osd_dev *od)
{
if (od && !IS_ERR(od)) {
struct osd_dev_handle *odh =
container_of(od, struct osd_dev_handle, od);
struct osd_uld_device *oud = odh->oud;
BUG_ON(od->scsi_device != oud->od.scsi_device);
/* If scsi has released the device (logout), and exofs has last
* reference on oud it will be freed by above osd_uld_release
* within fput below. But this will oops in cdev_release which
* is called after the fops->release. A get_/put_ pair makes
* sure we have a cdev for the duration of fput
*/
if (odh->file) {
get_device(&oud->class_dev);
fput(odh->file);
}
put_device(&oud->class_dev);
kfree(odh);
}
}
EXPORT_SYMBOL(osduld_put_device);
const struct osd_dev_info *osduld_device_info(struct osd_dev *od)
{
struct osd_dev_handle *odh =
container_of(od, struct osd_dev_handle, od);
return &odh->oud->odi;
}
EXPORT_SYMBOL(osduld_device_info);
bool osduld_device_same(struct osd_dev *od, const struct osd_dev_info *odi)
{
struct osd_dev_handle *odh =
container_of(od, struct osd_dev_handle, od);
struct osd_uld_device *oud = odh->oud;
return (oud->odi.systemid_len == odi->systemid_len) &&
_the_same_or_null(oud->odi.systemid, oud->odi.systemid_len,
odi->systemid, odi->systemid_len) &&
(oud->odi.osdname_len == odi->osdname_len) &&
_the_same_or_null(oud->odi.osdname, oud->odi.osdname_len,
odi->osdname, odi->osdname_len);
}
EXPORT_SYMBOL(osduld_device_same);
/*
* Scsi Device operations
*/
static int __detect_osd(struct osd_uld_device *oud)
{
struct scsi_device *scsi_device = oud->od.scsi_device;
char caps[OSD_CAP_LEN];
int error;
/* sending a test_unit_ready as first command seems to be needed
* by some targets
*/
OSD_DEBUG("start scsi_test_unit_ready %p %p %p\n",
oud, scsi_device, scsi_device->request_queue);
error = scsi_test_unit_ready(scsi_device, 10*HZ, 5, NULL);
if (error)
OSD_ERR("warning: scsi_test_unit_ready failed\n");
osd_sec_init_nosec_doall_caps(caps, &osd_root_object, false, true);
if (osd_auto_detect_ver(&oud->od, caps, &oud->odi))
return -ENODEV;
return 0;
}
static void __remove(struct device *dev)
{
struct osd_uld_device *oud = container_of(dev, struct osd_uld_device,
class_dev);
struct scsi_device *scsi_device = oud->od.scsi_device;
kfree(oud->odi.osdname);
if (oud->cdev.owner)
cdev_del(&oud->cdev);
osd_dev_fini(&oud->od);
scsi_device_put(scsi_device);
OSD_INFO("osd_remove %s\n",
oud->disk ? oud->disk->disk_name : NULL);
if (oud->disk)
put_disk(oud->disk);
ida_remove(&osd_minor_ida, oud->minor);
kfree(oud);
}
static int osd_probe(struct device *dev)
{
struct scsi_device *scsi_device = to_scsi_device(dev);
struct gendisk *disk;
struct osd_uld_device *oud;
int minor;
int error;
if (scsi_device->type != TYPE_OSD)
return -ENODEV;
do {
if (!ida_pre_get(&osd_minor_ida, GFP_KERNEL))
return -ENODEV;
error = ida_get_new(&osd_minor_ida, &minor);
} while (error == -EAGAIN);
if (error)
return error;
if (minor >= SCSI_OSD_MAX_MINOR) {
error = -EBUSY;
goto err_retract_minor;
}
error = -ENOMEM;
oud = kzalloc(sizeof(*oud), GFP_KERNEL);
if (NULL == oud)
goto err_retract_minor;
dev_set_drvdata(dev, oud);
oud->minor = minor;
/* allocate a disk and set it up */
/* FIXME: do we need this since sg has already done that */
disk = alloc_disk(1);
if (!disk) {
OSD_ERR("alloc_disk failed\n");
goto err_free_osd;
}
disk->major = SCSI_OSD_MAJOR;
disk->first_minor = oud->minor;
sprintf(disk->disk_name, "osd%d", oud->minor);
oud->disk = disk;
/* hold one more reference to the scsi_device that will get released
* in __release, in case a logout is happening while fs is mounted
*/
scsi_device_get(scsi_device);
osd_dev_init(&oud->od, scsi_device);
/* Detect the OSD Version */
error = __detect_osd(oud);
if (error) {
OSD_ERR("osd detection failed, non-compatible OSD device\n");
goto err_put_disk;
}
/* init the char-device for communication with user-mode */
cdev_init(&oud->cdev, &osd_fops);
oud->cdev.owner = THIS_MODULE;
error = cdev_add(&oud->cdev,
MKDEV(SCSI_OSD_MAJOR, oud->minor), 1);
if (error) {
OSD_ERR("cdev_add failed\n");
goto err_put_disk;
}
/* class device member */
oud->class_dev.devt = oud->cdev.dev;
oud->class_dev.class = &osd_uld_class;
oud->class_dev.parent = dev;
oud->class_dev.release = __remove;
error = dev_set_name(&oud->class_dev, disk->disk_name);
if (error) {
OSD_ERR("dev_set_name failed => %d\n", error);
goto err_put_cdev;
}
error = device_register(&oud->class_dev);
if (error) {
OSD_ERR("device_register failed => %d\n", error);
goto err_put_cdev;
}
get_device(&oud->class_dev);
OSD_INFO("osd_probe %s\n", disk->disk_name);
return 0;
err_put_cdev:
cdev_del(&oud->cdev);
err_put_disk:
scsi_device_put(scsi_device);
put_disk(disk);
err_free_osd:
dev_set_drvdata(dev, NULL);
kfree(oud);
err_retract_minor:
ida_remove(&osd_minor_ida, minor);
return error;
}
static int osd_remove(struct device *dev)
{
struct scsi_device *scsi_device = to_scsi_device(dev);
struct osd_uld_device *oud = dev_get_drvdata(dev);
if (!oud || (oud->od.scsi_device != scsi_device)) {
OSD_ERR("Half cooked osd-device %p,%p || %p!=%p",
dev, oud, oud ? oud->od.scsi_device : NULL,
scsi_device);
}
device_unregister(&oud->class_dev);
put_device(&oud->class_dev);
return 0;
}
/*
* Global driver and scsi registration
*/
static struct scsi_driver osd_driver = {
.owner = THIS_MODULE,
.gendrv = {
.name = osd_name,
.probe = osd_probe,
.remove = osd_remove,
}
};
static int __init osd_uld_init(void)
{
int err;
err = class_register(&osd_uld_class);
if (err) {
OSD_ERR("Unable to register sysfs class => %d\n", err);
return err;
}
err = register_chrdev_region(MKDEV(SCSI_OSD_MAJOR, 0),
SCSI_OSD_MAX_MINOR, osd_name);
if (err) {
OSD_ERR("Unable to register major %d for osd ULD => %d\n",
SCSI_OSD_MAJOR, err);
goto err_out;
}
err = scsi_register_driver(&osd_driver.gendrv);
if (err) {
OSD_ERR("scsi_register_driver failed => %d\n", err);
goto err_out_chrdev;
}
OSD_INFO("LOADED %s\n", osd_version_string);
return 0;
err_out_chrdev:
unregister_chrdev_region(MKDEV(SCSI_OSD_MAJOR, 0), SCSI_OSD_MAX_MINOR);
err_out:
class_unregister(&osd_uld_class);
return err;
}
static void __exit osd_uld_exit(void)
{
scsi_unregister_driver(&osd_driver.gendrv);
unregister_chrdev_region(MKDEV(SCSI_OSD_MAJOR, 0), SCSI_OSD_MAX_MINOR);
class_unregister(&osd_uld_class);
OSD_INFO("UNLOADED %s\n", osd_version_string);
}
module_init(osd_uld_init);
module_exit(osd_uld_exit);
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