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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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22
fs/hpfs/dentry.c
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@ -34,19 +34,25 @@ static int hpfs_hash_dentry(struct dentry *dentry, struct qstr *qstr)
return 0;
}
static int hpfs_compare_dentry(struct dentry *dentry, struct qstr *a, struct qstr *b)
static int hpfs_compare_dentry(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)
{
unsigned al=a->len;
unsigned bl=b->len;
hpfs_adjust_length(a->name, &al);
unsigned al = len;
unsigned bl = name->len;
hpfs_adjust_length(str, &al);
/*hpfs_adjust_length(b->name, &bl);*/
/* 'a' is the qstr of an already existing dentry, so the name
* must be valid. 'b' must be validated first.
/*
* 'str' is the nane of an already existing dentry, so the name
* must be valid. 'name' must be validated first.
*/
if (hpfs_chk_name(b->name, &bl))
if (hpfs_chk_name(name->name, &bl))
return 1;
if (hpfs_compare_names(dentry->d_sb, a->name, al, b->name, bl, 0))
if (hpfs_compare_names(parent->d_sb, str, al, name->name, bl, 0))
return 1;
return 0;
}