From: Russell King <rmk@arm.linux.org.uk>
To: "SATHISH.J" <sathish.j@tatainfotech.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Reg file system hash function
Date: Fri, 15 Jun 2001 11:30:38 +0100 [thread overview]
Message-ID: <20010615113038.B31502@flint.arm.linux.org.uk> (raw)
In-Reply-To: <Pine.LNX.4.10.10106141549470.11393-100000@blrmail> <Pine.LNX.4.10.10106151546310.5980-100000@blrmail>
In-Reply-To: <Pine.LNX.4.10.10106151546310.5980-100000@blrmail>; from sathish.j@tatainfotech.com on Fri, Jun 15, 2001 at 03:52:52PM +0530
On Fri, Jun 15, 2001 at 03:52:52PM +0530, SATHISH.J wrote:
> In the vfs layer when we see the lookup_dentry() function code we see that
> a part of the code checks whether low level filesystem wants to use its
> own hash. the part odf the code that calls the filesystem dependant
> hashing is "error = base->d_op->d_hash->(base,&this);". Why should it
> callfilesystem dependant hashing. What is the main purpose of hashing
> here.
> Please help me with these details.
It is used in two cases. If a filesystem has:
1. case-insensitive filenames (its much better to have the names 'FOO' and
'foo' refer to the same dentry, since they refer to the same file)
2. a limited filename length and your filesystem truncates names (on a
non-vfat filesystem 'dosfilen.ame' and 'dosfilename.ame' would be the
same file and the same dentry structure).
--
Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux
http://www.arm.linux.org.uk/personal/aboutme.html
next prev parent reply other threads:[~2001-06-15 10:31 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Pine.LNX.4.10.10106031716330.3971-100000@blrmail>
2001-06-04 16:34 ` Reg mkdir syscall SATHISH.J
2001-06-05 5:02 ` H. Peter Anvin
2001-06-08 6:26 ` Reg compiling of source code SATHISH.J
2001-06-14 7:52 ` Reg-directory size SATHISH.J
2001-06-14 8:53 ` Daniel Phillips
2001-06-14 10:23 ` RAM filesystem directory size SATHISH.J
2001-06-15 10:22 ` Reg file system hash function SATHISH.J
2001-06-15 10:30 ` Russell King [this message]
2001-06-17 8:06 ` Reg:dentry->d_mounts value SATHISH.J
2001-06-17 8:14 ` Reg:magic number of the filesystem SATHISH.J
2001-06-17 8:21 ` Reg:use of file_system_type structure SATHISH.J
2001-06-17 8:21 ` Alexander Viro
2001-06-18 7:56 ` function of getname() function SATHISH.J
2001-06-18 7:42 ` Alexander Viro
2001-06-18 7:47 ` Tigran Aivazian
2001-06-18 8:35 ` Reg:current a pointer to task_struct SATHISH.J
2001-06-18 8:49 ` Reg putname() function SATHISH.J
2001-06-18 9:06 ` Reg:current a pointer to task_struct george anzinger
2001-06-20 9:41 ` filldir() function SATHISH.J
2001-06-20 22:26 ` Jan Kara
2001-06-25 7:11 ` Reg Kernel Debugger kdb SATHISH.J
2001-06-25 7:33 ` siva kumar
2001-06-25 8:36 ` Keith Owens
2001-06-26 4:54 ` Reg Kernel Debugger kgdb SATHISH.J
2001-06-26 10:01 ` using gdb to debug kernel SATHISH.J
2001-06-26 10:57 ` Lars Marowsky-Bree
2001-06-26 11:10 ` Reg installing a patch on linux SATHISH.J
2001-06-26 16:17 ` Reg Kernel Debugger kgdb Timur Tabi
2001-06-21 12:06 ` Reg:use of file_system_type structure Anuradha Ratnaweera
2001-06-17 8:26 ` Reg:magic number of the filesystem Alexander Viro
2001-06-11 4:59 ` exec format error SATHISH.J
2001-06-11 6:08 ` David Woodhouse
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