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merge d_materialise_unique() into d_splice_alias()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
parent
154e80e4c3
commit
b5ae6b15bd
145
fs/dcache.c
145
fs/dcache.c
@ -2575,11 +2575,11 @@ struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
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* Note: If ever the locking in lock_rename() changes, then please
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* remember to update this too...
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*/
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static struct dentry *__d_unalias(struct inode *inode,
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static int __d_unalias(struct inode *inode,
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struct dentry *dentry, struct dentry *alias)
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{
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struct mutex *m1 = NULL, *m2 = NULL;
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struct dentry *ret = ERR_PTR(-EBUSY);
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int ret = -EBUSY;
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/* If alias and dentry share a parent, then no extra locks required */
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if (alias->d_parent == dentry->d_parent)
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@ -2594,7 +2594,7 @@ static struct dentry *__d_unalias(struct inode *inode,
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m2 = &alias->d_parent->d_inode->i_mutex;
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out_unalias:
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__d_move(alias, dentry, false);
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ret = alias;
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ret = 0;
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out_err:
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spin_unlock(&inode->i_lock);
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if (m2)
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@ -2629,130 +2629,57 @@ out_err:
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*/
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struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
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{
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struct dentry *new = NULL;
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if (IS_ERR(inode))
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return ERR_CAST(inode);
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if (inode && S_ISDIR(inode->i_mode)) {
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spin_lock(&inode->i_lock);
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new = __d_find_any_alias(inode);
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if (new) {
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if (!IS_ROOT(new)) {
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spin_unlock(&inode->i_lock);
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dput(new);
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iput(inode);
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return ERR_PTR(-EIO);
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}
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if (d_ancestor(new, dentry)) {
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spin_unlock(&inode->i_lock);
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dput(new);
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iput(inode);
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return ERR_PTR(-EIO);
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}
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write_seqlock(&rename_lock);
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__d_move(new, dentry, false);
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write_sequnlock(&rename_lock);
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spin_unlock(&inode->i_lock);
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security_d_instantiate(new, inode);
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iput(inode);
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} else {
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/* already taking inode->i_lock, so d_add() by hand */
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__d_instantiate(dentry, inode);
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spin_unlock(&inode->i_lock);
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security_d_instantiate(dentry, inode);
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d_rehash(dentry);
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}
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} else {
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d_instantiate(dentry, inode);
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if (d_unhashed(dentry))
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d_rehash(dentry);
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}
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return new;
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}
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EXPORT_SYMBOL(d_splice_alias);
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/**
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* d_materialise_unique - introduce an inode into the tree
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* @dentry: candidate dentry
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* @inode: inode to bind to the dentry, to which aliases may be attached
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*
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* Introduces an dentry into the tree, substituting an extant disconnected
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* root directory alias in its place if there is one. Caller must hold the
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* i_mutex of the parent directory.
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*/
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struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
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{
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struct dentry *actual;
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BUG_ON(!d_unhashed(dentry));
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if (!inode) {
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actual = dentry;
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__d_instantiate(dentry, NULL);
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d_rehash(actual);
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goto out_nolock;
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goto out;
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}
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spin_lock(&inode->i_lock);
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if (S_ISDIR(inode->i_mode)) {
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struct dentry *alias;
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/* Does an aliased dentry already exist? */
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alias = __d_find_alias(inode);
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if (alias) {
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actual = alias;
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struct dentry *new = __d_find_any_alias(inode);
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if (unlikely(new)) {
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write_seqlock(&rename_lock);
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if (d_ancestor(alias, dentry)) {
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/* Check for loops */
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actual = ERR_PTR(-ELOOP);
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spin_unlock(&inode->i_lock);
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} else if (IS_ROOT(alias)) {
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/* Is this an anonymous mountpoint that we
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* could splice into our tree? */
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__d_move(alias, dentry, false);
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if (unlikely(d_ancestor(new, dentry))) {
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write_sequnlock(&rename_lock);
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goto found;
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spin_unlock(&inode->i_lock);
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dput(new);
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new = ERR_PTR(-ELOOP);
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pr_warn_ratelimited(
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"VFS: Lookup of '%s' in %s %s"
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" would have caused loop\n",
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dentry->d_name.name,
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inode->i_sb->s_type->name,
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inode->i_sb->s_id);
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} else if (!IS_ROOT(new)) {
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int err = __d_unalias(inode, dentry, new);
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write_sequnlock(&rename_lock);
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if (err) {
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dput(new);
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new = ERR_PTR(err);
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}
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} else {
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/* Nope, but we must(!) avoid directory
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* aliasing. This drops inode->i_lock */
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actual = __d_unalias(inode, dentry, alias);
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__d_move(new, dentry, false);
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write_sequnlock(&rename_lock);
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spin_unlock(&inode->i_lock);
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security_d_instantiate(new, inode);
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}
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write_sequnlock(&rename_lock);
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if (IS_ERR(actual)) {
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if (PTR_ERR(actual) == -ELOOP)
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pr_warn_ratelimited(
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"VFS: Lookup of '%s' in %s %s"
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" would have caused loop\n",
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dentry->d_name.name,
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inode->i_sb->s_type->name,
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inode->i_sb->s_id);
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dput(alias);
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}
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goto out_nolock;
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iput(inode);
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return new;
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}
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}
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/* Add a unique reference */
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actual = __d_instantiate_unique(dentry, inode);
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if (!actual)
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actual = dentry;
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d_rehash(actual);
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found:
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/* already taking inode->i_lock, so d_add() by hand */
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__d_instantiate(dentry, inode);
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spin_unlock(&inode->i_lock);
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out_nolock:
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if (actual == dentry) {
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security_d_instantiate(dentry, inode);
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return NULL;
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}
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iput(inode);
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return actual;
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out:
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security_d_instantiate(dentry, inode);
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d_rehash(dentry);
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return NULL;
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}
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EXPORT_SYMBOL_GPL(d_materialise_unique);
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EXPORT_SYMBOL(d_splice_alias);
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static int prepend(char **buffer, int *buflen, const char *str, int namelen)
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{
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@ -230,7 +230,7 @@ extern seqlock_t rename_lock;
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*/
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extern void d_instantiate(struct dentry *, struct inode *);
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extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
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extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
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#define d_materialise_unique(d, i) d_splice_alias(i, d)
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extern int d_instantiate_no_diralias(struct dentry *, struct inode *);
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extern void __d_drop(struct dentry *dentry);
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extern void d_drop(struct dentry *dentry);
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