On Wed 17 Nov at 01:09:07 +1100 npiggin@xxxxxxxxx said:
> Index: linux-2.6/include/linux/dcache.h
> ===================================================================
> --- linux-2.6.orig/include/linux/dcache.h 2010-11-17 00:52:37.000000000 +1100
> +++ linux-2.6/include/linux/dcache.h 2010-11-17 01:05:48.000000000 +1100
> @@ -134,7 +134,9 @@ enum dentry_d_lock_class
> struct dentry_operations {
> int (*d_revalidate)(struct dentry *, struct nameidata *);
> int (*d_hash)(struct dentry *, struct qstr *);
> - int (*d_compare)(struct dentry *, struct qstr *, struct qstr *);
> + int (*d_compare)(const struct dentry *,
> + const struct dentry *, const struct inode *,
> + unsigned int, const char *, const struct qstr *);
> int (*d_delete)(const struct dentry *);
> void (*d_release)(struct dentry *);
> void (*d_iput)(struct dentry *, struct inode *);
The white space change I'd previously noted may as well happen here
if you're wanting it...just keeps the revision history cleaner for
future eyes.
> Index: linux-2.6/Documentation/filesystems/vfs.txt
> ===================================================================
> --- linux-2.6.orig/Documentation/filesystems/vfs.txt 2010-11-17 00:52:37.000000000 +1100
> +++ linux-2.6/Documentation/filesystems/vfs.txt 2010-11-17 01:05:49.000000000 +1100
> @@ -842,7 +842,9 @@ the VFS uses a default. As of kernel 2.6
> struct dentry_operations {
> int (*d_revalidate)(struct dentry *, struct nameidata *);
> int (*d_hash)(struct dentry *, struct qstr *);
> - int (*d_compare)(struct dentry *, struct qstr *, struct qstr *);
> + int (*d_compare)(const struct dentry *,
> + const struct dentry *, const struct inode *,
> + unsigned int, const char *, const struct qstr *);
> int (*d_delete)(const struct dentry *);
> void (*d_release)(struct dentry *);
> void (*d_iput)(struct dentry *, struct inode *);
Ditto.
> @@ -854,9 +856,26 @@ struct dentry_operations {
> dcache. Most filesystems leave this as NULL, because all their
> dentries in the dcache are valid
>
> - d_hash: called when the VFS adds a dentry to the hash table
> + d_hash: called when the VFS adds a dentry to the hash table. The first
> + dentry passed to d_hash is the parent directory that the name is
> + to be hashed into.
Similarly it'd be cleaner if this was in the next patch which is changing
d_hash(). Same for the d_hash() prototype white space changes.
>
> - d_compare: called when a dentry should be compared with another
> + d_compare: called to compare a dentry name with a given name. The first
> + dentry is the parent of the dentry to be compared, the second is
> + the dentry itself. inode, len, and name string are properties of
> + the dentry to be compared. qstr is the name to compare it with.
> +
> + Must be constant and idempotent, and should not take locks if
> + possible, and should not or store into the dentry or inodes.
^^^^^^^^^^^^^^^^
Verb missing? Or extra conjunction?
> + Should not dereference pointers outside the dentry or inodes without
> + lots of care (eg. d_parent, d_inode shouldn't be used).
> +
> + However, our vfsmount is pinned, and RCU held, so the dentries and
> + inodes won't disappear, neither will our sb or filesystem module.
> + ->i_sb and ->d_sb may be used.
> +
> + It is a tricky calling convention because it needs to be called under
> + "rcu-walk", ie. without any locks or references on things.
>
> d_delete: called when the last reference to a dentry is dropped and the
> dcache is deciding whether or not to cache it. Return 1 to delete
--
Tim Pepper <lnxninja@xxxxxxxxxxxxxxxxxx>
IBM Linux Technology Center
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