2011-02-22 13:58:44 +03:00
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/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2011, Fajar A. Nugraha. All rights reserved.
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* Use is subject to license terms.
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*/
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2014-10-29 04:29:53 +03:00
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#include <ctype.h>
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#include <string.h>
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2011-02-22 13:58:44 +03:00
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#include <stdio.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <linux/ioctl.h>
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#include <sys/stat.h>
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#include <sys/ioctl.h>
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#include <sys/zfs_znode.h>
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#include <sys/fs/zfs.h>
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2013-11-01 23:26:11 +04:00
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static int
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ioctl_get_msg(char *var, int fd)
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2011-02-22 13:58:44 +03:00
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{
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
int ret;
|
2016-06-16 00:28:36 +03:00
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|
|
char msg[ZFS_MAX_DATASET_NAME_LEN];
|
2011-02-22 13:58:44 +03:00
|
|
|
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
ret = ioctl(fd, BLKZNAME, msg);
|
|
|
|
|
if (ret < 0) {
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|
return (ret);
|
2011-02-22 13:58:44 +03:00
|
|
|
}
|
|
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|
2016-06-16 00:28:36 +03:00
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|
snprintf(var, ZFS_MAX_DATASET_NAME_LEN, "%s", msg);
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
return (ret);
|
2011-02-22 13:58:44 +03:00
|
|
|
}
|
|
|
|
|
|
2013-11-01 23:26:11 +04:00
|
|
|
int
|
|
|
|
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main(int argc, char **argv)
|
2011-02-22 13:58:44 +03:00
|
|
|
{
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
int fd = -1, ret = 0, status = EXIT_FAILURE;
|
2016-06-16 00:28:36 +03:00
|
|
|
char zvol_name[ZFS_MAX_DATASET_NAME_LEN];
|
2018-04-04 20:16:47 +03:00
|
|
|
char *zvol_name_part = NULL;
|
2011-02-22 13:58:44 +03:00
|
|
|
char *dev_name;
|
|
|
|
|
struct stat64 statbuf;
|
|
|
|
|
int dev_minor, dev_part;
|
2014-10-29 04:29:53 +03:00
|
|
|
int i;
|
2011-02-22 13:58:44 +03:00
|
|
|
|
|
|
|
|
if (argc < 2) {
|
Print zvol_id error messages to stderr rather than stdout
The zvol_id program is invoked by udev, via a PROGRAM key in the
60-zvol.rules.in rule file, to determine the "pretty" /dev/zvol/*
symlink paths paths that should be generated for each opaquely named
/dev/zd* dev node.
The udev rule uses the PROGRAM key, followed by a SYMLINK+= assignment
containing the %c substitution, to collect the program's stdout and then
"paste" it directly into the name of the symlink(s) to be created.
Unfortunately, as currently written, zvol_id outputs both its intended
output (a single string representing the symlink path that should be
created to refer to the name of the dataset whose /dev/zd* path is
given) AND its error messages (if any) to stdout.
When processing PROGRAM keys (and others, such as IMPORT{program}), udev
uses only the data written to stdout for functional purposes. Any data
written to stderr is used solely for the purposes of logging (if udev's
log_level is set to debug).
The unintended consequence of this is as follows: if zvol_id encounters
an error condition; and then udev fails to halt processing of the
current rule (either because zvol_id didn't return a nonzero exit
status, or because the PROGRAM key in the rule wasn't written properly
to result in a "non-match" condition that would stop the current rule on
a nonzero exit); then udev will create a space-delimited list of symlink
names derived directly from the words of the error message string!
I've observed this exact behavior on my own system, in a situation where
the open() syscall on /dev/zd* dev nodes was failing sporadically (for
reasons that aren't especially relevant here). Because the open() call
failed, zvol_id printed "Unable to open device file: /dev/zd736\n" to
stdout and then exited.
The udev rule finished with SYMLINK+="zvol/%c %c". Assuming a volume
name like pool/foo/bar, this would ordinarily expand to
SYMLINK+="zvol/pool/foo/bar pool/foo/bar"
and would cause symlinks to be created like this:
/dev/zvol/pool/foo/bar -> /dev/zd736
/dev/pool/foo/bar -> /dev/zd736
But because of the combination of error messages being printed to
stdout, and the udev syntax freely accepting a space-delimited sequence
of names in this context, the error message string
"Unable to open device file: /dev/zd736\n"
in reality expanded to
SYMLINK+="zvol/Unable to open device file: /dev/zd736"
which caused the following symlinks to actually be created:
/dev/zvol/Unable -> /dev/zd736
/dev/to -> /dev/zd736
/dev/open -> /dev/zd736
/dev/device -> /dev/zd736
/dev/file: -> /dev/zd736
/dev//dev/zd736 -> /dev/zd736
(And, because multiple zvols had open() syscall errors, multiple zvols
attempted to claim several of those symlink names, resulting in numerous
udev errors and timeouts and general chaos.)
This commit rectifies all this silliness by simply printing error
messages to stderr, as Dennis Ritchie originally intended.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 06:14:18 +03:00
|
|
|
fprintf(stderr, "Usage: %s /dev/zvol_device_node\n", argv[0]);
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
goto fail;
|
2011-02-22 13:58:44 +03:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
dev_name = argv[1];
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
ret = stat64(dev_name, &statbuf);
|
|
|
|
|
if (ret != 0) {
|
Print zvol_id error messages to stderr rather than stdout
The zvol_id program is invoked by udev, via a PROGRAM key in the
60-zvol.rules.in rule file, to determine the "pretty" /dev/zvol/*
symlink paths paths that should be generated for each opaquely named
/dev/zd* dev node.
The udev rule uses the PROGRAM key, followed by a SYMLINK+= assignment
containing the %c substitution, to collect the program's stdout and then
"paste" it directly into the name of the symlink(s) to be created.
Unfortunately, as currently written, zvol_id outputs both its intended
output (a single string representing the symlink path that should be
created to refer to the name of the dataset whose /dev/zd* path is
given) AND its error messages (if any) to stdout.
When processing PROGRAM keys (and others, such as IMPORT{program}), udev
uses only the data written to stdout for functional purposes. Any data
written to stderr is used solely for the purposes of logging (if udev's
log_level is set to debug).
The unintended consequence of this is as follows: if zvol_id encounters
an error condition; and then udev fails to halt processing of the
current rule (either because zvol_id didn't return a nonzero exit
status, or because the PROGRAM key in the rule wasn't written properly
to result in a "non-match" condition that would stop the current rule on
a nonzero exit); then udev will create a space-delimited list of symlink
names derived directly from the words of the error message string!
I've observed this exact behavior on my own system, in a situation where
the open() syscall on /dev/zd* dev nodes was failing sporadically (for
reasons that aren't especially relevant here). Because the open() call
failed, zvol_id printed "Unable to open device file: /dev/zd736\n" to
stdout and then exited.
The udev rule finished with SYMLINK+="zvol/%c %c". Assuming a volume
name like pool/foo/bar, this would ordinarily expand to
SYMLINK+="zvol/pool/foo/bar pool/foo/bar"
and would cause symlinks to be created like this:
/dev/zvol/pool/foo/bar -> /dev/zd736
/dev/pool/foo/bar -> /dev/zd736
But because of the combination of error messages being printed to
stdout, and the udev syntax freely accepting a space-delimited sequence
of names in this context, the error message string
"Unable to open device file: /dev/zd736\n"
in reality expanded to
SYMLINK+="zvol/Unable to open device file: /dev/zd736"
which caused the following symlinks to actually be created:
/dev/zvol/Unable -> /dev/zd736
/dev/to -> /dev/zd736
/dev/open -> /dev/zd736
/dev/device -> /dev/zd736
/dev/file: -> /dev/zd736
/dev//dev/zd736 -> /dev/zd736
(And, because multiple zvols had open() syscall errors, multiple zvols
attempted to claim several of those symlink names, resulting in numerous
udev errors and timeouts and general chaos.)
This commit rectifies all this silliness by simply printing error
messages to stderr, as Dennis Ritchie originally intended.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 06:14:18 +03:00
|
|
|
fprintf(stderr, "Unable to access device file: %s\n", dev_name);
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
goto fail;
|
2011-02-22 13:58:44 +03:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
dev_minor = minor(statbuf.st_rdev);
|
|
|
|
|
dev_part = dev_minor % ZVOL_MINORS;
|
|
|
|
|
|
|
|
|
|
fd = open(dev_name, O_RDONLY);
|
|
|
|
|
if (fd < 0) {
|
Print zvol_id error messages to stderr rather than stdout
The zvol_id program is invoked by udev, via a PROGRAM key in the
60-zvol.rules.in rule file, to determine the "pretty" /dev/zvol/*
symlink paths paths that should be generated for each opaquely named
/dev/zd* dev node.
The udev rule uses the PROGRAM key, followed by a SYMLINK+= assignment
containing the %c substitution, to collect the program's stdout and then
"paste" it directly into the name of the symlink(s) to be created.
Unfortunately, as currently written, zvol_id outputs both its intended
output (a single string representing the symlink path that should be
created to refer to the name of the dataset whose /dev/zd* path is
given) AND its error messages (if any) to stdout.
When processing PROGRAM keys (and others, such as IMPORT{program}), udev
uses only the data written to stdout for functional purposes. Any data
written to stderr is used solely for the purposes of logging (if udev's
log_level is set to debug).
The unintended consequence of this is as follows: if zvol_id encounters
an error condition; and then udev fails to halt processing of the
current rule (either because zvol_id didn't return a nonzero exit
status, or because the PROGRAM key in the rule wasn't written properly
to result in a "non-match" condition that would stop the current rule on
a nonzero exit); then udev will create a space-delimited list of symlink
names derived directly from the words of the error message string!
I've observed this exact behavior on my own system, in a situation where
the open() syscall on /dev/zd* dev nodes was failing sporadically (for
reasons that aren't especially relevant here). Because the open() call
failed, zvol_id printed "Unable to open device file: /dev/zd736\n" to
stdout and then exited.
The udev rule finished with SYMLINK+="zvol/%c %c". Assuming a volume
name like pool/foo/bar, this would ordinarily expand to
SYMLINK+="zvol/pool/foo/bar pool/foo/bar"
and would cause symlinks to be created like this:
/dev/zvol/pool/foo/bar -> /dev/zd736
/dev/pool/foo/bar -> /dev/zd736
But because of the combination of error messages being printed to
stdout, and the udev syntax freely accepting a space-delimited sequence
of names in this context, the error message string
"Unable to open device file: /dev/zd736\n"
in reality expanded to
SYMLINK+="zvol/Unable to open device file: /dev/zd736"
which caused the following symlinks to actually be created:
/dev/zvol/Unable -> /dev/zd736
/dev/to -> /dev/zd736
/dev/open -> /dev/zd736
/dev/device -> /dev/zd736
/dev/file: -> /dev/zd736
/dev//dev/zd736 -> /dev/zd736
(And, because multiple zvols had open() syscall errors, multiple zvols
attempted to claim several of those symlink names, resulting in numerous
udev errors and timeouts and general chaos.)
This commit rectifies all this silliness by simply printing error
messages to stderr, as Dennis Ritchie originally intended.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 06:14:18 +03:00
|
|
|
fprintf(stderr, "Unable to open device file: %s\n", dev_name);
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
goto fail;
|
2011-02-22 13:58:44 +03:00
|
|
|
}
|
|
|
|
|
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
ret = ioctl_get_msg(zvol_name, fd);
|
|
|
|
|
if (ret < 0) {
|
Print zvol_id error messages to stderr rather than stdout
The zvol_id program is invoked by udev, via a PROGRAM key in the
60-zvol.rules.in rule file, to determine the "pretty" /dev/zvol/*
symlink paths paths that should be generated for each opaquely named
/dev/zd* dev node.
The udev rule uses the PROGRAM key, followed by a SYMLINK+= assignment
containing the %c substitution, to collect the program's stdout and then
"paste" it directly into the name of the symlink(s) to be created.
Unfortunately, as currently written, zvol_id outputs both its intended
output (a single string representing the symlink path that should be
created to refer to the name of the dataset whose /dev/zd* path is
given) AND its error messages (if any) to stdout.
When processing PROGRAM keys (and others, such as IMPORT{program}), udev
uses only the data written to stdout for functional purposes. Any data
written to stderr is used solely for the purposes of logging (if udev's
log_level is set to debug).
The unintended consequence of this is as follows: if zvol_id encounters
an error condition; and then udev fails to halt processing of the
current rule (either because zvol_id didn't return a nonzero exit
status, or because the PROGRAM key in the rule wasn't written properly
to result in a "non-match" condition that would stop the current rule on
a nonzero exit); then udev will create a space-delimited list of symlink
names derived directly from the words of the error message string!
I've observed this exact behavior on my own system, in a situation where
the open() syscall on /dev/zd* dev nodes was failing sporadically (for
reasons that aren't especially relevant here). Because the open() call
failed, zvol_id printed "Unable to open device file: /dev/zd736\n" to
stdout and then exited.
The udev rule finished with SYMLINK+="zvol/%c %c". Assuming a volume
name like pool/foo/bar, this would ordinarily expand to
SYMLINK+="zvol/pool/foo/bar pool/foo/bar"
and would cause symlinks to be created like this:
/dev/zvol/pool/foo/bar -> /dev/zd736
/dev/pool/foo/bar -> /dev/zd736
But because of the combination of error messages being printed to
stdout, and the udev syntax freely accepting a space-delimited sequence
of names in this context, the error message string
"Unable to open device file: /dev/zd736\n"
in reality expanded to
SYMLINK+="zvol/Unable to open device file: /dev/zd736"
which caused the following symlinks to actually be created:
/dev/zvol/Unable -> /dev/zd736
/dev/to -> /dev/zd736
/dev/open -> /dev/zd736
/dev/device -> /dev/zd736
/dev/file: -> /dev/zd736
/dev//dev/zd736 -> /dev/zd736
(And, because multiple zvols had open() syscall errors, multiple zvols
attempted to claim several of those symlink names, resulting in numerous
udev errors and timeouts and general chaos.)
This commit rectifies all this silliness by simply printing error
messages to stderr, as Dennis Ritchie originally intended.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 06:14:18 +03:00
|
|
|
fprintf(stderr, "ioctl_get_msg failed: %s\n", strerror(errno));
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
goto fail;
|
2011-03-24 11:22:52 +03:00
|
|
|
}
|
2011-02-22 13:58:44 +03:00
|
|
|
if (dev_part > 0)
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
ret = asprintf(&zvol_name_part, "%s-part%d", zvol_name,
|
2018-04-04 20:16:47 +03:00
|
|
|
dev_part);
|
2011-02-22 13:58:44 +03:00
|
|
|
else
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
ret = asprintf(&zvol_name_part, "%s", zvol_name);
|
2018-04-04 20:16:47 +03:00
|
|
|
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
if (ret == -1 || zvol_name_part == NULL)
|
|
|
|
|
goto fail;
|
2011-02-22 13:58:44 +03:00
|
|
|
|
2014-10-29 04:29:53 +03:00
|
|
|
for (i = 0; i < strlen(zvol_name_part); i++) {
|
|
|
|
|
if (isblank(zvol_name_part[i]))
|
|
|
|
|
zvol_name_part[i] = '+';
|
|
|
|
|
}
|
|
|
|
|
|
2011-02-22 13:58:44 +03:00
|
|
|
printf("%s\n", zvol_name_part);
|
Use substantially more robust program exit status logic in zvol_id
Currently, there are several places in zvol_id where the program logic
returns particular errno values, or even particular ioctl return values,
as the program exit status, rather than a straightforward system of
explicit zero on success and explicit nonzero value(s) on failure.
This is problematic for multiple reasons. One particularly interesting
problem that can arise, is that if any of these values happens to have
all 8 least significant bits unset (i.e., it is a positive or negative
multiple of 256), then although the C program sees a nonzero int value
(presumed to be a failure exit status), the actual exit status as seen
by the system is only the bottom 8 bits of that integer: zero.
This can happen in practice, and I have encountered it myself. In a
particularly weird situation, the zvol_open code in the zfs kernel
module was behaving in such a manner that it caused the open() syscall
to fail and for errno to be set to a kernel-private value (ERESTARTSYS,
which happens to be defined as 512). It turns out that 512 is evenly
divisible by 256; or, in other words, its least significant 8 bits are
all-zero. So even though zvol_id believed it was returning a nonzero
(failure) exit status of 512, the system modulo'd that value by 256,
resulting in the actual exit status visible by other programs being 0!
This actually-zero (non-failure) exit status caused problems: udev
believed that the program was operating successfully, when in fact it
was attempting to indicate failure via a nonzero exit status integer.
Combined with another problem, this led to the creation of nonsense
symlinks for zvol dev nodes by udev.
Let's get rid of all this problematic logic, and simply return
EXIT_SUCCESS (0) is everything went fine, and EXIT_FAILURE (1) if
anything went wrong.
Additionally, let's clarify some of the variable names (error is similar
to errno, etc) and clean up the overall program flow a bit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Justin Gottula <justin@jgottula.com>
Closes #12302
2021-06-30 07:29:09 +03:00
|
|
|
status = EXIT_SUCCESS;
|
|
|
|
|
|
|
|
|
|
fail:
|
|
|
|
|
if (zvol_name_part)
|
|
|
|
|
free(zvol_name_part);
|
|
|
|
|
if (fd >= 0)
|
|
|
|
|
close(fd);
|
|
|
|
|
|
|
|
|
|
return (status);
|
2011-02-22 13:58:44 +03:00
|
|
|
}
|