Re: How to get the inode - no path_lookup
On Thu, Aug 9, 2012 at 12:39 PM, Rohan Puri rohan.pur...@gmail.com wrote:
On Thu, Aug 9, 2012 at 8:45 AM, Rishi Agrawal
rishi.b.agra...@gmail.comwrote:
On Wed, Aug 8, 2012 at 12:46 PM, Rohan Puri rohan.pur...@gmail.comwrote:
On Tue, Aug 7, 2012 at 8:11 PM, Rishi Agrawal rishi.b.agra...@gmail.com
wrote:
Hi All,
I had a module which used the path_lookup function to print the details
of any file's inode. I now want to rewrite that module in order to show
some juniors how to write some code in kernel.
I am using 3.4.6 kernel, I tried finding out path_lookup but google
showed that it has been removed.
I tried the following code then which did not work
.
.
.
dentry = kern_path_create(AT_FDCWD, filename, path, 1);
if (IS_ERR(dentry)) {
printk(Failed to obtain the dentry);
return;
}
its not returning dentry
I again tried after seeing the implementation of vfs_stat function
user_path_at(AT_FDCWD, filename, lookup_flags, path);
but this also fails.
I am using a proc interface to pass the filename, and copying the
filename into a kernel buffer.
How can I get a copy of vfs inode for a file name.
Need to use vfs_path_lookup for this, present in fs/namei.c file, which
would give you filled nameidata nd that contais inodes pointer.
--
Regards,
Rishi Agrawal
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- Rohan
vfs_path_lookup needs a dentry/mountpoint for the current path.
How will I get those.
/**
* vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
* @dentry: pointer to dentry of the base directory
* @mnt: pointer to vfs mount of the base directory
* @name: pointer to file name
* @flags: lookup flags
* @path: pointer to struct path to fill
*/
--
Regards,
Rishi Agrawal
If you dont have vfsmount's ptr, then you can make use of kern_path api
with the LOOKUP_FOLLOW as second parameter. This will return the struct
path ptr which contains vfsmount and the dentry's ptr. Now the dentry's ptr
will contain the inode that you require.
- Rohan
Thanks, used that and its working now
--
Regards,
Rishi Agrawal
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Re: How to get the inode - no path_lookup
On Mon, Aug 13, 2012 at 2:17 PM, Rishi Agrawal rishi.b.agra...@gmail.comwrote:
On Thu, Aug 9, 2012 at 12:39 PM, Rohan Puri rohan.pur...@gmail.comwrote:
On Thu, Aug 9, 2012 at 8:45 AM, Rishi Agrawal
rishi.b.agra...@gmail.comwrote:
On Wed, Aug 8, 2012 at 12:46 PM, Rohan Puri rohan.pur...@gmail.comwrote:
On Tue, Aug 7, 2012 at 8:11 PM, Rishi Agrawal
rishi.b.agra...@gmail.com wrote:
Hi All,
I had a module which used the path_lookup function to print the
details of any file's inode. I now want to rewrite that module in order to
show some juniors how to write some code in kernel.
I am using 3.4.6 kernel, I tried finding out path_lookup but google
showed that it has been removed.
I tried the following code then which did not work
.
.
.
dentry = kern_path_create(AT_FDCWD, filename, path, 1);
if (IS_ERR(dentry)) {
printk(Failed to obtain the dentry);
return;
}
its not returning dentry
I again tried after seeing the implementation of vfs_stat function
user_path_at(AT_FDCWD, filename, lookup_flags, path);
but this also fails.
I am using a proc interface to pass the filename, and copying the
filename into a kernel buffer.
How can I get a copy of vfs inode for a file name.
Need to use vfs_path_lookup for this, present in fs/namei.c file,
which would give you filled nameidata nd that contais inodes pointer.
--
Regards,
Rishi Agrawal
___
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- Rohan
vfs_path_lookup needs a dentry/mountpoint for the current path.
How will I get those.
/**
* vfs_path_lookup - lookup a file path relative to a dentry-vfsmount
pair
* @dentry: pointer to dentry of the base directory
* @mnt: pointer to vfs mount of the base directory
* @name: pointer to file name
* @flags: lookup flags
* @path: pointer to struct path to fill
*/
--
Regards,
Rishi Agrawal
If you dont have vfsmount's ptr, then you can make use of kern_path api
with the LOOKUP_FOLLOW as second parameter. This will return the struct
path ptr which contains vfsmount and the dentry's ptr. Now the dentry's ptr
will contain the inode that you require.
- Rohan
Thanks, used that and its working now
--
Regards,
Rishi Agrawal
Good to know :)
- Rohan
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HI, How KGDB works internally or how a gdb stub works internally with source code for x86_64 arch. Can some one please suggest me the good docs for the same.I am very new to this so want know whole detailed internally working procedure for KGDB. Thanks Vivek ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re:
2012/8/13 Vivek Panwar vivekpanwar2...@gmail.com HI, How KGDB works internally or how a gdb stub works internally with source code for x86_64 arch. Can some one please suggest me the good docs for the same.I am very new to this so want know whole detailed internally working procedure for KGDB. Thanks Vivek ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies you can refer to this doc, see as the accessary to build you kgdb environment. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re:
Thanks a lot . On Mon, Aug 13, 2012 at 4:31 PM, Fan Yang lljyang...@gmail.com wrote: 2012/8/13 Vivek Panwar vivekpanwar2...@gmail.com HI, How KGDB works internally or how a gdb stub works internally with source code for x86_64 arch. Can some one please suggest me the good docs for the same.I am very new to this so want know whole detailed internally working procedure for KGDB. Thanks Vivek ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re:
On Mon, Aug 13, 2012 at 12:04 PM, Vivek Panwar vivekpanwar2...@gmail.comwrote: Thanks a lot . On Mon, Aug 13, 2012 at 4:31 PM, Fan Yang lljyang...@gmail.com wrote: 2012/8/13 Vivek Panwar vivekpanwar2...@gmail.com HI, How KGDB works internally or how a gdb stub works internally with source code for x86_64 arch. Can some one please suggest me the good docs for the same.I am very new to this so want know whole detailed internally working procedure for KGDB. Thanks Vivek Please always use a subject line. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: invoking zcache w/o using a workload
Thanks Mulyadi for your response. zcache has cleancache (a third level page cache) and front swap(swap cache). I am trying to trigger clean cache and now the swap device. But my guess is reducing the memory should also cause these evictions rapidly. Thanks, Asim On Sun, Aug 12, 2012 at 11:56 PM, Mulyadi Santosa mulyadi.sant...@gmail.com wrote: Hi... On Mon, Aug 13, 2012 at 3:58 AM, Asim linka...@gmail.com wrote: Is there a way I can trigger zcache_get/put (specifically clean cache) with a simple unit test (as opposed to running a workload) ? This will greatly reduce my test/build time. I am a new user of zcache (due to playing with recent Mint release). I got impression that by reducing mapped memory you have (using mem= kernel parameter) and putting zram/zcache into high priority swap, is enough to quickly trigger allocation into zcache. of course, you need memory hogger for that, something like tail -f /dev/zero. CMIIW if misunderstood you... -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: How to understand the macro __init?
Hi.. :) On Tue, Aug 14, 2012 at 9:14 AM, 王哲 wangzhe5...@gmail.com wrote: i use the __init for function print_k. in my opinion after the fisrt invoking the print_k in the hello_init. the memory of print_k will be freed,and the second invoking will not be executed.but the result of second invoking is executing . why? because you're still in module_init :) right after modul init stage is done, _init marked function is thrown away... -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
