Added a new enum to decide if we want to sleep in uninterruptible or
killable state or we want simply to return immediately.
Signed-off-by: Marco Stornelli <[email protected]>
---
fs/super.c | 24 ++++++++++++++++++------
include/linux/fs.h | 19 +++++++++++++------
2 files changed, 31 insertions(+), 12 deletions(-)
diff --git a/fs/super.c b/fs/super.c
index 7465d43..6b70c7f 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1190,14 +1190,25 @@ static void acquire_freeze_lock(struct super_block *sb, int level, bool trylock,
* This is an internal function, please use sb_start_{write,pagefault,intwrite}
* instead.
*/
-int __sb_start_write(struct super_block *sb, int level, bool wait)
+int __sb_start_write(struct super_block *sb, int level, int wait)
{
+ int ret = 0;
retry:
if (unlikely(sb->s_writers.frozen >= level)) {
- if (!wait)
- return 0;
- wait_event(sb->s_writers.wait_unfrozen,
- sb->s_writers.frozen < level);
+ switch (wait) {
+ case FREEZE_NOWAIT:
+ return ret;
+ case FREEZE_WAIT:
+ wait_event(sb->s_writers.wait_unfrozen,
+ sb->s_writers.frozen < level);
+ break;
+ case FREEZE_WAIT_KILLABLE:
+ ret = wait_event_killable(sb->s_writers.wait_unfrozen,
+ sb->s_writers.frozen < level);
+ if (ret)
+ return -EINTR;
+ break;
+ }
}
#ifdef CONFIG_LOCKDEP
@@ -1213,7 +1224,8 @@ retry:
__sb_end_write(sb, level);
goto retry;
}
- return 1;
+ ret = 1;
+ return ret;
}
EXPORT_SYMBOL(__sb_start_write);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 8d47c9a..c8b7325 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1220,6 +1220,13 @@ enum {
#define SB_FREEZE_LEVELS (SB_FREEZE_COMPLETE - 1)
+/* Possible waiting modes */
+enum {
+ FREEZE_NOWAIT = 0, /* no blocking call */
+ FREEZE_WAIT = 1, /* wait in uninterruptible state */
+ FREEZE_WAIT_KILLABLE = 2, /* wait in killable state */
+};
+
struct sb_writers {
/* Counters for counting writers at each level */
struct percpu_counter counter[SB_FREEZE_LEVELS];
@@ -1335,7 +1342,7 @@ extern struct timespec current_fs_time(struct super_block *sb);
*/
void __sb_end_write(struct super_block *sb, int level);
-int __sb_start_write(struct super_block *sb, int level, bool wait);
+int __sb_start_write(struct super_block *sb, int level, int wait);
/**
* sb_end_write - drop write access to a superblock
@@ -1394,12 +1401,12 @@ static inline void sb_end_intwrite(struct super_block *sb)
*/
static inline void sb_start_write(struct super_block *sb)
{
- __sb_start_write(sb, SB_FREEZE_WRITE, true);
+ __sb_start_write(sb, SB_FREEZE_WRITE, FREEZE_WAIT);
}
static inline int sb_start_write_trylock(struct super_block *sb)
{
- return __sb_start_write(sb, SB_FREEZE_WRITE, false);
+ return __sb_start_write(sb, SB_FREEZE_WRITE, FREEZE_NOWAIT);
}
/**
@@ -1423,7 +1430,7 @@ static inline int sb_start_write_trylock(struct super_block *sb)
*/
static inline void sb_start_pagefault(struct super_block *sb)
{
- __sb_start_write(sb, SB_FREEZE_PAGEFAULT, true);
+ __sb_start_write(sb, SB_FREEZE_PAGEFAULT, FREEZE_WAIT);
}
/*
@@ -1441,7 +1448,7 @@ static inline void sb_start_pagefault(struct super_block *sb)
*/
static inline void sb_start_intwrite(struct super_block *sb)
{
- __sb_start_write(sb, SB_FREEZE_FS, true);
+ __sb_start_write(sb, SB_FREEZE_FS, FREEZE_WAIT);
}
@@ -2224,7 +2231,7 @@ static inline void file_start_write(struct file *file)
{
if (!S_ISREG(file_inode(file)->i_mode))
return;
- __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);
+ __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, FREEZE_WAIT);
}
static inline void file_end_write(struct file *file)
--
1.7.3.4
On Sat 13-04-13 12:35:54, Marco Stornelli wrote:
> Added a new enum to decide if we want to sleep in uninterruptible or
> killable state or we want simply to return immediately.
I like the patch. You can add:
Reviewed-by: Jan Kara <[email protected]>
Honza
>
> Signed-off-by: Marco Stornelli <[email protected]>
> ---
> fs/super.c | 24 ++++++++++++++++++------
> include/linux/fs.h | 19 +++++++++++++------
> 2 files changed, 31 insertions(+), 12 deletions(-)
>
> diff --git a/fs/super.c b/fs/super.c
> index 7465d43..6b70c7f 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -1190,14 +1190,25 @@ static void acquire_freeze_lock(struct super_block *sb, int level, bool trylock,
> * This is an internal function, please use sb_start_{write,pagefault,intwrite}
> * instead.
> */
> -int __sb_start_write(struct super_block *sb, int level, bool wait)
> +int __sb_start_write(struct super_block *sb, int level, int wait)
> {
> + int ret = 0;
> retry:
> if (unlikely(sb->s_writers.frozen >= level)) {
> - if (!wait)
> - return 0;
> - wait_event(sb->s_writers.wait_unfrozen,
> - sb->s_writers.frozen < level);
> + switch (wait) {
> + case FREEZE_NOWAIT:
> + return ret;
> + case FREEZE_WAIT:
> + wait_event(sb->s_writers.wait_unfrozen,
> + sb->s_writers.frozen < level);
> + break;
> + case FREEZE_WAIT_KILLABLE:
> + ret = wait_event_killable(sb->s_writers.wait_unfrozen,
> + sb->s_writers.frozen < level);
> + if (ret)
> + return -EINTR;
> + break;
> + }
> }
>
> #ifdef CONFIG_LOCKDEP
> @@ -1213,7 +1224,8 @@ retry:
> __sb_end_write(sb, level);
> goto retry;
> }
> - return 1;
> + ret = 1;
> + return ret;
> }
> EXPORT_SYMBOL(__sb_start_write);
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 8d47c9a..c8b7325 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1220,6 +1220,13 @@ enum {
>
> #define SB_FREEZE_LEVELS (SB_FREEZE_COMPLETE - 1)
>
> +/* Possible waiting modes */
> +enum {
> + FREEZE_NOWAIT = 0, /* no blocking call */
> + FREEZE_WAIT = 1, /* wait in uninterruptible state */
> + FREEZE_WAIT_KILLABLE = 2, /* wait in killable state */
> +};
> +
> struct sb_writers {
> /* Counters for counting writers at each level */
> struct percpu_counter counter[SB_FREEZE_LEVELS];
> @@ -1335,7 +1342,7 @@ extern struct timespec current_fs_time(struct super_block *sb);
> */
>
> void __sb_end_write(struct super_block *sb, int level);
> -int __sb_start_write(struct super_block *sb, int level, bool wait);
> +int __sb_start_write(struct super_block *sb, int level, int wait);
>
> /**
> * sb_end_write - drop write access to a superblock
> @@ -1394,12 +1401,12 @@ static inline void sb_end_intwrite(struct super_block *sb)
> */
> static inline void sb_start_write(struct super_block *sb)
> {
> - __sb_start_write(sb, SB_FREEZE_WRITE, true);
> + __sb_start_write(sb, SB_FREEZE_WRITE, FREEZE_WAIT);
> }
>
> static inline int sb_start_write_trylock(struct super_block *sb)
> {
> - return __sb_start_write(sb, SB_FREEZE_WRITE, false);
> + return __sb_start_write(sb, SB_FREEZE_WRITE, FREEZE_NOWAIT);
> }
>
> /**
> @@ -1423,7 +1430,7 @@ static inline int sb_start_write_trylock(struct super_block *sb)
> */
> static inline void sb_start_pagefault(struct super_block *sb)
> {
> - __sb_start_write(sb, SB_FREEZE_PAGEFAULT, true);
> + __sb_start_write(sb, SB_FREEZE_PAGEFAULT, FREEZE_WAIT);
> }
>
> /*
> @@ -1441,7 +1448,7 @@ static inline void sb_start_pagefault(struct super_block *sb)
> */
> static inline void sb_start_intwrite(struct super_block *sb)
> {
> - __sb_start_write(sb, SB_FREEZE_FS, true);
> + __sb_start_write(sb, SB_FREEZE_FS, FREEZE_WAIT);
> }
>
>
> @@ -2224,7 +2231,7 @@ static inline void file_start_write(struct file *file)
> {
> if (!S_ISREG(file_inode(file)->i_mode))
> return;
> - __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);
> + __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, FREEZE_WAIT);
> }
>
> static inline void file_end_write(struct file *file)
> --
> 1.7.3.4
--
Jan Kara <[email protected]>
SUSE Labs, CR
Resend due to mail client problem.
Marco
2013/4/17 Marco Stornelli <[email protected]>
>
> Hi,
>
>
> 2013/4/15 Jan Kara <[email protected]>
>>
>> On Sat 13-04-13 12:35:54, Marco Stornelli wrote:
>> > Added a new enum to decide if we want to sleep in uninterruptible or
>> > killable state or we want simply to return immediately.
>> I like the patch. You can add:
>> Reviewed-by: Jan Kara <[email protected]>
>>
>> Honza
>>
>
I'm happy if we can include the patches. However I do an update about
the on-going and additional work: the patches submitted can be
applied as-is, however, I'm still working on extending the killable
path in mnt_want_write/mnt_want_write_file and I'm seeing if it's
possible to change even the page_mkwrite path. In the first case, as
Al said, there are three clear "hot" points, do_last, kern_path_create
and mq_open. However I modified the code carefully in these code paths
and I did some basic tests and it works. I'm going to submit the patch
next week for a review if I'm able to do more tests.
About the page_mkwrite path and the return value VM_FAULT_RETRY: the
return value of get_user_pages can be 0 in case of VM_FAULT_RETRY. The
caller set the nonblocking flag and it can manage the situation.
Blocking callers, instead, have a BUG_ON on the return value of 0.
They want either an error code or the number of pages gotten. A little
modification of __get_user_pages can do the work. However,
page_mkwrite could return VM_FAULT_RETRY even if the flag
FAULT_FLAG_ALLOW_RETRY is not set, I don't know if it's correct and
this flag in each case, at the moment, it's not visibile in
page_mkwrite. In addition, I need to understand if a skip can be
useful, or in each case the process will go to sleep in
uninterruptible state in a step forward. Any comments is welcome.
Marco