refcount_t type and corresponding API can protect refcounters from
accidental underflow and overflow and further use-after-free situations.
Signed-off-by: Xiyu Yang <[email protected]>
Signed-off-by: Xin Tan <[email protected]>
---
fs/ceph/snap.c | 15 ++++++++-------
fs/ceph/super.h | 3 ++-
2 files changed, 10 insertions(+), 8 deletions(-)
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index 4ac0606dcbd4..d4ec9c5118bd 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -68,14 +68,15 @@ void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
lockdep_assert_held(&mdsc->snap_rwsem);
dout("get_realm %p %d -> %d\n", realm,
- atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
+ refcount_read(&realm->nref), refcount_read(&realm->nref)+1);
/*
* since we _only_ increment realm refs or empty the empty
* list with snap_rwsem held, adjusting the empty list here is
* safe. we do need to protect against concurrent empty list
* additions, however.
*/
- if (atomic_inc_return(&realm->nref) == 1) {
+ refcount_inc(&realm->nref);
+ if (refcount_read(&realm->nref) == 1) {
spin_lock(&mdsc->snap_empty_lock);
list_del_init(&realm->empty_item);
spin_unlock(&mdsc->snap_empty_lock);
@@ -121,7 +122,7 @@ static struct ceph_snap_realm *ceph_create_snap_realm(
if (!realm)
return ERR_PTR(-ENOMEM);
- atomic_set(&realm->nref, 1); /* for caller */
+ refcount_set(&realm->nref, 1); /* for caller */
realm->ino = ino;
INIT_LIST_HEAD(&realm->children);
INIT_LIST_HEAD(&realm->child_item);
@@ -209,8 +210,8 @@ static void __put_snap_realm(struct ceph_mds_client *mdsc,
lockdep_assert_held_write(&mdsc->snap_rwsem);
dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
- atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
- if (atomic_dec_and_test(&realm->nref))
+ refcount_read(&realm->nref), refcount_read(&realm->nref)-1);
+ if (refcount_dec_and_test(&realm->nref))
__destroy_snap_realm(mdsc, realm);
}
@@ -221,8 +222,8 @@ void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
struct ceph_snap_realm *realm)
{
dout("put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
- atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
- if (!atomic_dec_and_test(&realm->nref))
+ refcount_read(&realm->nref), refcount_read(&realm->nref)-1);
+ if (!refcount_dec_and_test(&realm->nref))
return;
if (down_write_trylock(&mdsc->snap_rwsem)) {
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 6b6332a5c113..3abb00d7a0eb 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -2,6 +2,7 @@
#ifndef _FS_CEPH_SUPER_H
#define _FS_CEPH_SUPER_H
+#include <linux/refcount.h>
#include <linux/ceph/ceph_debug.h>
#include <asm/unaligned.h>
@@ -859,7 +860,7 @@ struct ceph_readdir_cache_control {
struct ceph_snap_realm {
u64 ino;
struct inode *inode;
- atomic_t nref;
+ refcount_t nref;
struct rb_node node;
u64 created, seq;
--
2.7.4
On Sat, 2021-07-17 at 18:06 +0800, Xiyu Yang wrote:
> refcount_t type and corresponding API can protect refcounters from
> accidental underflow and overflow and further use-after-free situations.
>
> Signed-off-by: Xiyu Yang <[email protected]>
> Signed-off-by: Xin Tan <[email protected]>
> ---
> fs/ceph/snap.c | 15 ++++++++-------
> fs/ceph/super.h | 3 ++-
> 2 files changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
> index 4ac0606dcbd4..d4ec9c5118bd 100644
> --- a/fs/ceph/snap.c
> +++ b/fs/ceph/snap.c
> @@ -68,14 +68,15 @@ void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
> lockdep_assert_held(&mdsc->snap_rwsem);
>
> dout("get_realm %p %d -> %d\n", realm,
> - atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
> + refcount_read(&realm->nref), refcount_read(&realm->nref)+1);
> /*
> * since we _only_ increment realm refs or empty the empty
> * list with snap_rwsem held, adjusting the empty list here is
> * safe. we do need to protect against concurrent empty list
> * additions, however.
> */
> - if (atomic_inc_return(&realm->nref) == 1) {
> + refcount_inc(&realm->nref);
> + if (refcount_read(&realm->nref) == 1) {
The above is potentially racy as you've turned a single atomic operation
into two. Another task could come in and increment or decrement
realm->nref just after your recount_inc but before the refcount_read,
and then the read would show the wrong result.
FWIW, Yejune Deng (cc'ed) proposed a very similar patch a few months ago
that caused this regression:
https://tracker.ceph.com/issues/50281
> spin_lock(&mdsc->snap_empty_lock);
> list_del_init(&realm->empty_item);
> spin_unlock(&mdsc->snap_empty_lock);
> @@ -121,7 +122,7 @@ static struct ceph_snap_realm *ceph_create_snap_realm(
> if (!realm)
> return ERR_PTR(-ENOMEM);
>
> - atomic_set(&realm->nref, 1); /* for caller */
> + refcount_set(&realm->nref, 1); /* for caller */
> realm->ino = ino;
> INIT_LIST_HEAD(&realm->children);
> INIT_LIST_HEAD(&realm->child_item);
> @@ -209,8 +210,8 @@ static void __put_snap_realm(struct ceph_mds_client *mdsc,
> lockdep_assert_held_write(&mdsc->snap_rwsem);
>
> dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
> - atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
> - if (atomic_dec_and_test(&realm->nref))
> + refcount_read(&realm->nref), refcount_read(&realm->nref)-1);
> + if (refcount_dec_and_test(&realm->nref))
> __destroy_snap_realm(mdsc, realm);
> }
>
> @@ -221,8 +222,8 @@ void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
> struct ceph_snap_realm *realm)
> {
> dout("put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
> - atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
> - if (!atomic_dec_and_test(&realm->nref))
> + refcount_read(&realm->nref), refcount_read(&realm->nref)-1);
> + if (!refcount_dec_and_test(&realm->nref))
> return;
>
> if (down_write_trylock(&mdsc->snap_rwsem)) {
> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> index 6b6332a5c113..3abb00d7a0eb 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -2,6 +2,7 @@
> #ifndef _FS_CEPH_SUPER_H
> #define _FS_CEPH_SUPER_H
>
> +#include <linux/refcount.h>
> #include <linux/ceph/ceph_debug.h>
>
> #include <asm/unaligned.h>
> @@ -859,7 +860,7 @@ struct ceph_readdir_cache_control {
> struct ceph_snap_realm {
> u64 ino;
> struct inode *inode;
> - atomic_t nref;
> + refcount_t nref;
> struct rb_node node;
>
> u64 created, seq;
--
Jeff Layton <[email protected]>
Thank you for pointing out the problem in the patch. I cannot find an unique refcount API work like atomic_inc_return, thus I chose two APIs to play a similar role and forgot the potential racy case. So are you have a better choice to help this refcount type convertation?
> -----Original Messages-----
> From: "Jeff Layton" <[email protected]>
> Sent Time: 2021-07-17 19:21:40 (Saturday)
> To: "Xiyu Yang" <[email protected]>, "Ilya Dryomov" <[email protected]>, [email protected], [email protected]
> Cc: [email protected], "Xin Tan" <[email protected]>, "Yejune Deng" <[email protected]>
> Subject: Re: [PATCH] ceph: Convert from atomic_t to refcount_t on ceph_snap_realm->nref
>
> On Sat, 2021-07-17 at 18:06 +0800, Xiyu Yang wrote:
> > refcount_t type and corresponding API can protect refcounters from
> > accidental underflow and overflow and further use-after-free situations.
> >
> > Signed-off-by: Xiyu Yang <[email protected]>
> > Signed-off-by: Xin Tan <[email protected]>
> > ---
> > fs/ceph/snap.c | 15 ++++++++-------
> > fs/ceph/super.h | 3 ++-
> > 2 files changed, 10 insertions(+), 8 deletions(-)
> >
> > diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
> > index 4ac0606dcbd4..d4ec9c5118bd 100644
> > --- a/fs/ceph/snap.c
> > +++ b/fs/ceph/snap.c
> > @@ -68,14 +68,15 @@ void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
> > lockdep_assert_held(&mdsc->snap_rwsem);
> >
> > dout("get_realm %p %d -> %d\n", realm,
> > - atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
> > + refcount_read(&realm->nref), refcount_read(&realm->nref)+1);
> > /*
> > * since we _only_ increment realm refs or empty the empty
> > * list with snap_rwsem held, adjusting the empty list here is
> > * safe. we do need to protect against concurrent empty list
> > * additions, however.
> > */
> > - if (atomic_inc_return(&realm->nref) == 1) {
> > + refcount_inc(&realm->nref);
> > + if (refcount_read(&realm->nref) == 1) {
>
> The above is potentially racy as you've turned a single atomic operation
> into two. Another task could come in and increment or decrement
> realm->nref just after your recount_inc but before the refcount_read,
> and then the read would show the wrong result.
>
> FWIW, Yejune Deng (cc'ed) proposed a very similar patch a few months ago
> that caused this regression:
>
> https://tracker.ceph.com/issues/50281
>
> > spin_lock(&mdsc->snap_empty_lock);
> > list_del_init(&realm->empty_item);
> > spin_unlock(&mdsc->snap_empty_lock);
> > @@ -121,7 +122,7 @@ static struct ceph_snap_realm *ceph_create_snap_realm(
> > if (!realm)
> > return ERR_PTR(-ENOMEM);
> >
> > - atomic_set(&realm->nref, 1); /* for caller */
> > + refcount_set(&realm->nref, 1); /* for caller */
> > realm->ino = ino;
> > INIT_LIST_HEAD(&realm->children);
> > INIT_LIST_HEAD(&realm->child_item);
> > @@ -209,8 +210,8 @@ static void __put_snap_realm(struct ceph_mds_client *mdsc,
> > lockdep_assert_held_write(&mdsc->snap_rwsem);
> >
> > dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
> > - atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
> > - if (atomic_dec_and_test(&realm->nref))
> > + refcount_read(&realm->nref), refcount_read(&realm->nref)-1);
> > + if (refcount_dec_and_test(&realm->nref))
> > __destroy_snap_realm(mdsc, realm);
> > }
> >
> > @@ -221,8 +222,8 @@ void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
> > struct ceph_snap_realm *realm)
> > {
> > dout("put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
> > - atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
> > - if (!atomic_dec_and_test(&realm->nref))
> > + refcount_read(&realm->nref), refcount_read(&realm->nref)-1);
> > + if (!refcount_dec_and_test(&realm->nref))
> > return;
> >
> > if (down_write_trylock(&mdsc->snap_rwsem)) {
> > diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> > index 6b6332a5c113..3abb00d7a0eb 100644
> > --- a/fs/ceph/super.h
> > +++ b/fs/ceph/super.h
> > @@ -2,6 +2,7 @@
> > #ifndef _FS_CEPH_SUPER_H
> > #define _FS_CEPH_SUPER_H
> >
> > +#include <linux/refcount.h>
> > #include <linux/ceph/ceph_debug.h>
> >
> > #include <asm/unaligned.h>
> > @@ -859,7 +860,7 @@ struct ceph_readdir_cache_control {
> > struct ceph_snap_realm {
> > u64 ino;
> > struct inode *inode;
> > - atomic_t nref;
> > + refcount_t nref;
> > struct rb_node node;
> >
> > u64 created, seq;
>
> --
> Jeff Layton <[email protected]>
I think this is probably a place where we just can't reasonably convert
to using refcount_t, as the lifecycle of the refcounted objects doesn't
fully conform to the "standard" refcount_t model.
It may also be possible to extend the refcount_t API with a
refcount_inc_return or something, but I'm not sure that really gains us
much here.
-- Jeff
On Sat, 2021-07-17 at 20:26 +0800, Xiyu Yang wrote:
> Thank you for pointing out the problem in the patch. I cannot find an unique refcount API work like atomic_inc_return, thus I chose two APIs to play a similar role and forgot the potential racy case. So are you have a better choice to help this refcount type convertation?
>
>
> > -----Original Messages-----
> > From: "Jeff Layton" <[email protected]>
> > Sent Time: 2021-07-17 19:21:40 (Saturday)
> > To: "Xiyu Yang" <[email protected]>, "Ilya Dryomov" <[email protected]>, [email protected], [email protected]
> > Cc: [email protected], "Xin Tan" <[email protected]>, "Yejune Deng" <[email protected]>
> > Subject: Re: [PATCH] ceph: Convert from atomic_t to refcount_t on ceph_snap_realm->nref
> >
> > On Sat, 2021-07-17 at 18:06 +0800, Xiyu Yang wrote:
> > > refcount_t type and corresponding API can protect refcounters from
> > > accidental underflow and overflow and further use-after-free situations.
> > >
> > > Signed-off-by: Xiyu Yang <[email protected]>
> > > Signed-off-by: Xin Tan <[email protected]>
> > > ---
> > > fs/ceph/snap.c | 15 ++++++++-------
> > > fs/ceph/super.h | 3 ++-
> > > 2 files changed, 10 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
> > > index 4ac0606dcbd4..d4ec9c5118bd 100644
> > > --- a/fs/ceph/snap.c
> > > +++ b/fs/ceph/snap.c
> > > @@ -68,14 +68,15 @@ void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
> > > lockdep_assert_held(&mdsc->snap_rwsem);
> > >
> > > dout("get_realm %p %d -> %d\n", realm,
> > > - atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
> > > + refcount_read(&realm->nref), refcount_read(&realm->nref)+1);
> > > /*
> > > * since we _only_ increment realm refs or empty the empty
> > > * list with snap_rwsem held, adjusting the empty list here is
> > > * safe. we do need to protect against concurrent empty list
> > > * additions, however.
> > > */
> > > - if (atomic_inc_return(&realm->nref) == 1) {
> > > + refcount_inc(&realm->nref);
> > > + if (refcount_read(&realm->nref) == 1) {
> >
> > The above is potentially racy as you've turned a single atomic operation
> > into two. Another task could come in and increment or decrement
> > realm->nref just after your recount_inc but before the refcount_read,
> > and then the read would show the wrong result.
> >
> > FWIW, Yejune Deng (cc'ed) proposed a very similar patch a few months ago
> > that caused this regression:
> >
> > https://tracker.ceph.com/issues/50281
> >
> > > spin_lock(&mdsc->snap_empty_lock);
> > > list_del_init(&realm->empty_item);
> > > spin_unlock(&mdsc->snap_empty_lock);
> > > @@ -121,7 +122,7 @@ static struct ceph_snap_realm *ceph_create_snap_realm(
> > > if (!realm)
> > > return ERR_PTR(-ENOMEM);
> > >
> > > - atomic_set(&realm->nref, 1); /* for caller */
> > > + refcount_set(&realm->nref, 1); /* for caller */
> > > realm->ino = ino;
> > > INIT_LIST_HEAD(&realm->children);
> > > INIT_LIST_HEAD(&realm->child_item);
> > > @@ -209,8 +210,8 @@ static void __put_snap_realm(struct ceph_mds_client *mdsc,
> > > lockdep_assert_held_write(&mdsc->snap_rwsem);
> > >
> > > dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
> > > - atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
> > > - if (atomic_dec_and_test(&realm->nref))
> > > + refcount_read(&realm->nref), refcount_read(&realm->nref)-1);
> > > + if (refcount_dec_and_test(&realm->nref))
> > > __destroy_snap_realm(mdsc, realm);
> > > }
> > >
> > > @@ -221,8 +222,8 @@ void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
> > > struct ceph_snap_realm *realm)
> > > {
> > > dout("put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
> > > - atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
> > > - if (!atomic_dec_and_test(&realm->nref))
> > > + refcount_read(&realm->nref), refcount_read(&realm->nref)-1);
> > > + if (!refcount_dec_and_test(&realm->nref))
> > > return;
> > >
> > > if (down_write_trylock(&mdsc->snap_rwsem)) {
> > > diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> > > index 6b6332a5c113..3abb00d7a0eb 100644
> > > --- a/fs/ceph/super.h
> > > +++ b/fs/ceph/super.h
> > > @@ -2,6 +2,7 @@
> > > #ifndef _FS_CEPH_SUPER_H
> > > #define _FS_CEPH_SUPER_H
> > >
> > > +#include <linux/refcount.h>
> > > #include <linux/ceph/ceph_debug.h>
> > >
> > > #include <asm/unaligned.h>
> > > @@ -859,7 +860,7 @@ struct ceph_readdir_cache_control {
> > > struct ceph_snap_realm {
> > > u64 ino;
> > > struct inode *inode;
> > > - atomic_t nref;
> > > + refcount_t nref;
> > > struct rb_node node;
> > >
> > > u64 created, seq;
> >
> > --
> > Jeff Layton <[email protected]>
>
>
>
>
>
>
--
Jeff Layton <[email protected]>
Hi Xiyu,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on ceph-client/for-linus]
[also build test WARNING on v5.14-rc1 next-20210716]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Xiyu-Yang/ceph-Convert-from-atomic_t-to-refcount_t-on-ceph_snap_realm-nref/20210718-111108
base: https://github.com/ceph/ceph-client.git for-linus
config: arm-randconfig-r034-20210718 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 5d5b08761f944d5b9822d582378333cc4b36a0a7)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install arm cross compiling tool for clang build
# apt-get install binutils-arm-linux-gnueabi
# https://github.com/0day-ci/linux/commit/af8e5c68ccb6a1e5aead78e10d6d0441c032ba66
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Xiyu-Yang/ceph-Convert-from-atomic_t-to-refcount_t-on-ceph_snap_realm-nref/20210718-111108
git checkout af8e5c68ccb6a1e5aead78e10d6d0441c032ba66
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
All warnings (new ones prefixed by >>):
In file included from fs/ceph/quota.c:10:
In file included from fs/ceph/super.h:6:
>> include/linux/ceph/ceph_debug.h:5:9: warning: 'pr_fmt' macro redefined [-Wmacro-redefined]
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
^
include/linux/printk.h:301:9: note: previous definition is here
#define pr_fmt(fmt) fmt
^
1 warning generated.
vim +/pr_fmt +5 include/linux/ceph/ceph_debug.h
de57606c23afde fs/ceph/ceph_debug.h Sage Weil 2009-10-06 4
de57606c23afde fs/ceph/ceph_debug.h Sage Weil 2009-10-06 @5 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
de57606c23afde fs/ceph/ceph_debug.h Sage Weil 2009-10-06 6
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]
Hi Xiyu,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on ceph-client/for-linus]
[also build test WARNING on v5.14-rc1 next-20210716]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Xiyu-Yang/ceph-Convert-from-atomic_t-to-refcount_t-on-ceph_snap_realm-nref/20210718-111108
base: https://github.com/ceph/ceph-client.git for-linus
config: arc-randconfig-r016-20210718 (attached as .config)
compiler: arceb-elf-gcc (GCC) 10.3.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/af8e5c68ccb6a1e5aead78e10d6d0441c032ba66
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Xiyu-Yang/ceph-Convert-from-atomic_t-to-refcount_t-on-ceph_snap_realm-nref/20210718-111108
git checkout af8e5c68ccb6a1e5aead78e10d6d0441c032ba66
# save the attached .config to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.3.0 make.cross O=build_dir ARCH=arc SHELL=/bin/bash fs/ceph/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
All warnings (new ones prefixed by >>):
In file included from fs/ceph/super.h:6,
from fs/ceph/quota.c:10:
>> include/linux/ceph/ceph_debug.h:5: warning: "pr_fmt" redefined
5 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
|
In file included from include/linux/kernel.h:17,
from include/asm-generic/bug.h:20,
from arch/arc/include/asm/bug.h:30,
from include/linux/bug.h:5,
from include/linux/refcount.h:96,
from fs/ceph/super.h:5,
from fs/ceph/quota.c:10:
include/linux/printk.h:301: note: this is the location of the previous definition
301 | #define pr_fmt(fmt) fmt
|
vim +/pr_fmt +5 include/linux/ceph/ceph_debug.h
de57606c23afde fs/ceph/ceph_debug.h Sage Weil 2009-10-06 4
de57606c23afde fs/ceph/ceph_debug.h Sage Weil 2009-10-06 @5 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
de57606c23afde fs/ceph/ceph_debug.h Sage Weil 2009-10-06 6
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