fs: change d_compare for rcu-walk
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>
diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c
index 3345aab..99d3c7a 100644
--- a/fs/fat/namei_msdos.c
+++ b/fs/fat/namei_msdos.c
@@ -164,16 +164,18 @@
* Compare two msdos names. If either of the names are invalid,
* we fall back to doing the standard name comparison.
*/
-static int msdos_cmp(struct dentry *dentry, struct qstr *a, struct qstr *b)
+static int msdos_cmp(const struct dentry *parent, const struct inode *pinode,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options;
+ struct fat_mount_options *options = &MSDOS_SB(parent->d_sb)->options;
unsigned char a_msdos_name[MSDOS_NAME], b_msdos_name[MSDOS_NAME];
int error;
- error = msdos_format_name(a->name, a->len, a_msdos_name, options);
+ error = msdos_format_name(name->name, name->len, a_msdos_name, options);
if (error)
goto old_compare;
- error = msdos_format_name(b->name, b->len, b_msdos_name, options);
+ error = msdos_format_name(str, len, b_msdos_name, options);
if (error)
goto old_compare;
error = memcmp(a_msdos_name, b_msdos_name, MSDOS_NAME);
@@ -182,8 +184,8 @@
old_compare:
error = 1;
- if (a->len == b->len)
- error = memcmp(a->name, b->name, a->len);
+ if (name->len == len)
+ error = memcmp(name->name, str, len);
goto out;
}