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fs: change d_compare for rcu-walk

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Change d_compare so it may be called from lock-free RCU lookups. This
does put significant restrictions on what may be done from the callback,
however there don't seem to have been any problems with in-tree fses.
If some strange use case pops up that _really_ cannot cope with the
rcu-walk rules, we can just add new rcu-unaware callbacks, which would
cause name lookup to drop out of rcu-walk mode.

For in-tree filesystems, this is just a mechanical change.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
This commit is contained in:
Nick Piggin
2011-01-07 17:49:27 +11:00
parent fb2d5b86af
commit 621e155a35
23 changed files with 242 additions and 157 deletions
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12
include/linux/dcache.h
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@ -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 inode *,
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 *);
@ -145,12 +147,8 @@ struct dentry_operations {
* Locking rules for dentry_operations callbacks are to be found in
* Documentation/filesystems/Locking. Keep it updated!
*
* the dentry parameter passed to d_hash and d_compare is the parent
* directory of the entries to be compared. It is used in case these
* functions need any directory specific information for determining
* equivalency classes. Using the dentry itself might not work, as it
* might be a negative dentry which has no information associated with
* it.
* FUrther descriptions are found in Documentation/filesystems/vfs.txt.
* Keep it updated too!
*/
/* d_flags entries */