From 8665bd53f2f2e27e5511d90428cb3f60e6d0ce15 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 18 May 2024 20:50:12 +0200 Subject: Merging upstream version 6.8.9. Signed-off-by: Daniel Baumann --- fs/dcache.c | 647 ++++++++++++++++++++++-------------------------------------- 1 file changed, 237 insertions(+), 410 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index d1ab857a69..6ebccba333 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -51,8 +51,8 @@ * - d_lru * - d_count * - d_unhashed() - * - d_parent and d_subdirs - * - childrens' d_child and d_parent + * - d_parent and d_chilren + * - childrens' d_sib and d_parent * - d_u.d_alias, d_inode * * Ordering: @@ -191,7 +191,6 @@ static struct ctl_table fs_dcache_sysctls[] = { .mode = 0444, .proc_handler = proc_nr_dentry, }, - { } }; static int __init init_fs_dcache_sysctls(void) @@ -344,7 +343,7 @@ static inline void __d_set_inode_and_type(struct dentry *dentry, dentry->d_inode = inode; flags = READ_ONCE(dentry->d_flags); - flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU); + flags &= ~DCACHE_ENTRY_TYPE; flags |= type_flags; smp_store_release(&dentry->d_flags, flags); } @@ -353,7 +352,7 @@ static inline void __d_clear_type_and_inode(struct dentry *dentry) { unsigned flags = READ_ONCE(dentry->d_flags); - flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU); + flags &= ~DCACHE_ENTRY_TYPE; WRITE_ONCE(dentry->d_flags, flags); dentry->d_inode = NULL; if (dentry->d_flags & DCACHE_LRU_LIST) @@ -428,7 +427,8 @@ static void d_lru_add(struct dentry *dentry) this_cpu_inc(nr_dentry_unused); if (d_is_negative(dentry)) this_cpu_inc(nr_dentry_negative); - WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); + WARN_ON_ONCE(!list_lru_add_obj( + &dentry->d_sb->s_dentry_lru, &dentry->d_lru)); } static void d_lru_del(struct dentry *dentry) @@ -438,7 +438,8 @@ static void d_lru_del(struct dentry *dentry) this_cpu_dec(nr_dentry_unused); if (d_is_negative(dentry)) this_cpu_dec(nr_dentry_negative); - WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); + WARN_ON_ONCE(!list_lru_del_obj( + &dentry->d_sb->s_dentry_lru, &dentry->d_lru)); } static void d_shrink_del(struct dentry *dentry) @@ -537,7 +538,7 @@ void d_drop(struct dentry *dentry) } EXPORT_SYMBOL(d_drop); -static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent) +static inline void dentry_unlist(struct dentry *dentry) { struct dentry *next; /* @@ -545,12 +546,12 @@ static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent) * attached to the dentry tree */ dentry->d_flags |= DCACHE_DENTRY_KILLED; - if (unlikely(list_empty(&dentry->d_child))) + if (unlikely(hlist_unhashed(&dentry->d_sib))) return; - __list_del_entry(&dentry->d_child); + __hlist_del(&dentry->d_sib); /* * Cursors can move around the list of children. While we'd been - * a normal list member, it didn't matter - ->d_child.next would've + * a normal list member, it didn't matter - ->d_sib.next would've * been updated. However, from now on it won't be and for the * things like d_walk() it might end up with a nasty surprise. * Normally d_walk() doesn't care about cursors moving around - @@ -558,29 +559,27 @@ static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent) * of its own, we get through it without ever unlocking the parent. * There is one exception, though - if we ascend from a child that * gets killed as soon as we unlock it, the next sibling is found - * using the value left in its ->d_child.next. And if _that_ + * using the value left in its ->d_sib.next. And if _that_ * pointed to a cursor, and cursor got moved (e.g. by lseek()) * before d_walk() regains parent->d_lock, we'll end up skipping * everything the cursor had been moved past. * - * Solution: make sure that the pointer left behind in ->d_child.next + * Solution: make sure that the pointer left behind in ->d_sib.next * points to something that won't be moving around. I.e. skip the * cursors. */ - while (dentry->d_child.next != &parent->d_subdirs) { - next = list_entry(dentry->d_child.next, struct dentry, d_child); + while (dentry->d_sib.next) { + next = hlist_entry(dentry->d_sib.next, struct dentry, d_sib); if (likely(!(next->d_flags & DCACHE_DENTRY_CURSOR))) break; - dentry->d_child.next = next->d_child.next; + dentry->d_sib.next = next->d_sib.next; } } -static void __dentry_kill(struct dentry *dentry) +static struct dentry *__dentry_kill(struct dentry *dentry) { struct dentry *parent = NULL; bool can_free = true; - if (!IS_ROOT(dentry)) - parent = dentry->d_parent; /* * The dentry is now unrecoverably dead to the world. @@ -600,9 +599,6 @@ static void __dentry_kill(struct dentry *dentry) } /* if it was on the hash then remove it */ __d_drop(dentry); - dentry_unlist(dentry, parent); - if (parent) - spin_unlock(&parent->d_lock); if (dentry->d_inode) dentry_unlink_inode(dentry); else @@ -611,80 +607,114 @@ static void __dentry_kill(struct dentry *dentry) if (dentry->d_op && dentry->d_op->d_release) dentry->d_op->d_release(dentry); - spin_lock(&dentry->d_lock); - if (dentry->d_flags & DCACHE_SHRINK_LIST) { - dentry->d_flags |= DCACHE_MAY_FREE; - can_free = false; + cond_resched(); + /* now that it's negative, ->d_parent is stable */ + if (!IS_ROOT(dentry)) { + parent = dentry->d_parent; + spin_lock(&parent->d_lock); } + spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); + dentry_unlist(dentry); + if (dentry->d_flags & DCACHE_SHRINK_LIST) + can_free = false; spin_unlock(&dentry->d_lock); if (likely(can_free)) dentry_free(dentry); - cond_resched(); -} - -static struct dentry *__lock_parent(struct dentry *dentry) -{ - struct dentry *parent; - rcu_read_lock(); - spin_unlock(&dentry->d_lock); -again: - parent = READ_ONCE(dentry->d_parent); - spin_lock(&parent->d_lock); - /* - * We can't blindly lock dentry until we are sure - * that we won't violate the locking order. - * Any changes of dentry->d_parent must have - * been done with parent->d_lock held, so - * spin_lock() above is enough of a barrier - * for checking if it's still our child. - */ - if (unlikely(parent != dentry->d_parent)) { + if (parent && --parent->d_lockref.count) { spin_unlock(&parent->d_lock); - goto again; + return NULL; } - rcu_read_unlock(); - if (parent != dentry) - spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); - else - parent = NULL; return parent; } -static inline struct dentry *lock_parent(struct dentry *dentry) +/* + * Lock a dentry for feeding it to __dentry_kill(). + * Called under rcu_read_lock() and dentry->d_lock; the former + * guarantees that nothing we access will be freed under us. + * Note that dentry is *not* protected from concurrent dentry_kill(), + * d_delete(), etc. + * + * Return false if dentry is busy. Otherwise, return true and have + * that dentry's inode locked. + */ + +static bool lock_for_kill(struct dentry *dentry) { - struct dentry *parent = dentry->d_parent; - if (IS_ROOT(dentry)) - return NULL; - if (likely(spin_trylock(&parent->d_lock))) - return parent; - return __lock_parent(dentry); + struct inode *inode = dentry->d_inode; + + if (unlikely(dentry->d_lockref.count)) + return false; + + if (!inode || likely(spin_trylock(&inode->i_lock))) + return true; + + do { + spin_unlock(&dentry->d_lock); + spin_lock(&inode->i_lock); + spin_lock(&dentry->d_lock); + if (likely(inode == dentry->d_inode)) + break; + spin_unlock(&inode->i_lock); + inode = dentry->d_inode; + } while (inode); + if (likely(!dentry->d_lockref.count)) + return true; + if (inode) + spin_unlock(&inode->i_lock); + return false; } -static inline bool retain_dentry(struct dentry *dentry) +/* + * Decide if dentry is worth retaining. Usually this is called with dentry + * locked; if not locked, we are more limited and might not be able to tell + * without a lock. False in this case means "punt to locked path and recheck". + * + * In case we aren't locked, these predicates are not "stable". However, it is + * sufficient that at some point after we dropped the reference the dentry was + * hashed and the flags had the proper value. Other dentry users may have + * re-gotten a reference to the dentry and change that, but our work is done - + * we can leave the dentry around with a zero refcount. + */ +static inline bool retain_dentry(struct dentry *dentry, bool locked) { - WARN_ON(d_in_lookup(dentry)); + unsigned int d_flags; - /* Unreachable? Get rid of it */ + smp_rmb(); + d_flags = READ_ONCE(dentry->d_flags); + + // Unreachable? Nobody would be able to look it up, no point retaining if (unlikely(d_unhashed(dentry))) return false; - if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) + // Same if it's disconnected + if (unlikely(d_flags & DCACHE_DISCONNECTED)) return false; - if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) { - if (dentry->d_op->d_delete(dentry)) + // ->d_delete() might tell us not to bother, but that requires + // ->d_lock; can't decide without it + if (unlikely(d_flags & DCACHE_OP_DELETE)) { + if (!locked || dentry->d_op->d_delete(dentry)) return false; } - if (unlikely(dentry->d_flags & DCACHE_DONTCACHE)) + // Explicitly told not to bother + if (unlikely(d_flags & DCACHE_DONTCACHE)) return false; - /* retain; LRU fodder */ - dentry->d_lockref.count--; - if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST))) + // At this point it looks like we ought to keep it. We also might + // need to do something - put it on LRU if it wasn't there already + // and mark it referenced if it was on LRU, but not marked yet. + // Unfortunately, both actions require ->d_lock, so in lockless + // case we'd have to punt rather than doing those. + if (unlikely(!(d_flags & DCACHE_LRU_LIST))) { + if (!locked) + return false; d_lru_add(dentry); - else if (unlikely(!(dentry->d_flags & DCACHE_REFERENCED))) + } else if (unlikely(!(d_flags & DCACHE_REFERENCED))) { + if (!locked) + return false; dentry->d_flags |= DCACHE_REFERENCED; + } return true; } @@ -703,61 +733,12 @@ void d_mark_dontcache(struct inode *inode) } EXPORT_SYMBOL(d_mark_dontcache); -/* - * Finish off a dentry we've decided to kill. - * dentry->d_lock must be held, returns with it unlocked. - * Returns dentry requiring refcount drop, or NULL if we're done. - */ -static struct dentry *dentry_kill(struct dentry *dentry) - __releases(dentry->d_lock) -{ - struct inode *inode = dentry->d_inode; - struct dentry *parent = NULL; - - if (inode && unlikely(!spin_trylock(&inode->i_lock))) - goto slow_positive; - - if (!IS_ROOT(dentry)) { - parent = dentry->d_parent; - if (unlikely(!spin_trylock(&parent->d_lock))) { - parent = __lock_parent(dentry); - if (likely(inode || !dentry->d_inode)) - goto got_locks; - /* negative that became positive */ - if (parent) - spin_unlock(&parent->d_lock); - inode = dentry->d_inode; - goto slow_positive; - } - } - __dentry_kill(dentry); - return parent; - -slow_positive: - spin_unlock(&dentry->d_lock); - spin_lock(&inode->i_lock); - spin_lock(&dentry->d_lock); - parent = lock_parent(dentry); -got_locks: - if (unlikely(dentry->d_lockref.count != 1)) { - dentry->d_lockref.count--; - } else if (likely(!retain_dentry(dentry))) { - __dentry_kill(dentry); - return parent; - } - /* we are keeping it, after all */ - if (inode) - spin_unlock(&inode->i_lock); - if (parent) - spin_unlock(&parent->d_lock); - spin_unlock(&dentry->d_lock); - return NULL; -} - /* * Try to do a lockless dput(), and return whether that was successful. * * If unsuccessful, we return false, having already taken the dentry lock. + * In that case refcount is guaranteed to be zero and we have already + * decided that it's not worth keeping around. * * The caller needs to hold the RCU read lock, so that the dentry is * guaranteed to stay around even if the refcount goes down to zero! @@ -765,18 +746,9 @@ got_locks: static inline bool fast_dput(struct dentry *dentry) { int ret; - unsigned int d_flags; /* - * If we have a d_op->d_delete() operation, we sould not - * let the dentry count go to zero, so use "put_or_lock". - */ - if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) - return lockref_put_or_lock(&dentry->d_lockref); - - /* - * .. otherwise, we can try to just decrement the - * lockref optimistically. + * try to decrement the lockref optimistically. */ ret = lockref_put_return(&dentry->d_lockref); @@ -802,45 +774,18 @@ static inline bool fast_dput(struct dentry *dentry) return true; /* - * Careful, careful. The reference count went down - * to zero, but we don't hold the dentry lock, so - * somebody else could get it again, and do another - * dput(), and we need to not race with that. - * - * However, there is a very special and common case - * where we don't care, because there is nothing to - * do: the dentry is still hashed, it does not have - * a 'delete' op, and it's referenced and already on - * the LRU list. - * - * NOTE! Since we aren't locked, these values are - * not "stable". However, it is sufficient that at - * some point after we dropped the reference the - * dentry was hashed and the flags had the proper - * value. Other dentry users may have re-gotten - * a reference to the dentry and change that, but - * our work is done - we can leave the dentry - * around with a zero refcount. - * - * Nevertheless, there are two cases that we should kill - * the dentry anyway. - * 1. free disconnected dentries as soon as their refcount - * reached zero. - * 2. free dentries if they should not be cached. + * Can we decide that decrement of refcount is all we needed without + * taking the lock? There's a very common case when it's all we need - + * dentry looks like it ought to be retained and there's nothing else + * to do. */ - smp_rmb(); - d_flags = READ_ONCE(dentry->d_flags); - d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST | - DCACHE_DISCONNECTED | DCACHE_DONTCACHE; - - /* Nothing to do? Dropping the reference was all we needed? */ - if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry)) + if (retain_dentry(dentry, false)) return true; /* - * Not the fast normal case? Get the lock. We've already decremented - * the refcount, but we'll need to re-check the situation after - * getting the lock. + * Either not worth retaining or we can't tell without the lock. + * Get the lock, then. We've already decremented the refcount to 0, + * but we'll need to re-check the situation after getting the lock. */ spin_lock(&dentry->d_lock); @@ -851,17 +796,10 @@ static inline bool fast_dput(struct dentry *dentry) * don't need to do anything else. */ locked: - if (dentry->d_lockref.count) { + if (dentry->d_lockref.count || retain_dentry(dentry, true)) { spin_unlock(&dentry->d_lock); return true; } - - /* - * Re-get the reference we optimistically dropped. We hold the - * lock, and we just tested that it was zero, so we can just - * set it to 1. - */ - dentry->d_lockref.count = 1; return false; } @@ -894,39 +832,37 @@ locked: */ void dput(struct dentry *dentry) { - while (dentry) { - might_sleep(); - - rcu_read_lock(); - if (likely(fast_dput(dentry))) { - rcu_read_unlock(); - return; - } - - /* Slow case: now with the dentry lock held */ + if (!dentry) + return; + might_sleep(); + rcu_read_lock(); + if (likely(fast_dput(dentry))) { rcu_read_unlock(); - - if (likely(retain_dentry(dentry))) { + return; + } + while (lock_for_kill(dentry)) { + rcu_read_unlock(); + dentry = __dentry_kill(dentry); + if (!dentry) + return; + if (retain_dentry(dentry, true)) { spin_unlock(&dentry->d_lock); return; } - - dentry = dentry_kill(dentry); + rcu_read_lock(); } + rcu_read_unlock(); + spin_unlock(&dentry->d_lock); } EXPORT_SYMBOL(dput); -static void __dput_to_list(struct dentry *dentry, struct list_head *list) +static void to_shrink_list(struct dentry *dentry, struct list_head *list) __must_hold(&dentry->d_lock) { - if (dentry->d_flags & DCACHE_SHRINK_LIST) { - /* let the owner of the list it's on deal with it */ - --dentry->d_lockref.count; - } else { + if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) { if (dentry->d_flags & DCACHE_LRU_LIST) d_lru_del(dentry); - if (!--dentry->d_lockref.count) - d_shrink_add(dentry, list); + d_shrink_add(dentry, list); } } @@ -938,22 +874,10 @@ void dput_to_list(struct dentry *dentry, struct list_head *list) return; } rcu_read_unlock(); - if (!retain_dentry(dentry)) - __dput_to_list(dentry, list); + to_shrink_list(dentry, list); spin_unlock(&dentry->d_lock); } -/* This must be called with d_lock held */ -static inline void __dget_dlock(struct dentry *dentry) -{ - dentry->d_lockref.count++; -} - -static inline void __dget(struct dentry *dentry) -{ - lockref_get(&dentry->d_lockref); -} - struct dentry *dget_parent(struct dentry *dentry) { int gotref; @@ -1003,7 +927,7 @@ static struct dentry * __d_find_any_alias(struct inode *inode) if (hlist_empty(&inode->i_dentry)) return NULL; alias = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias); - __dget(alias); + lockref_get(&alias->d_lockref); return alias; } @@ -1035,7 +959,7 @@ static struct dentry *__d_find_alias(struct inode *inode) hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { spin_lock(&alias->d_lock); if (!d_unhashed(alias)) { - __dget_dlock(alias); + dget_dlock(alias); spin_unlock(&alias->d_lock); return alias; } @@ -1102,104 +1026,53 @@ struct dentry *d_find_alias_rcu(struct inode *inode) */ void d_prune_aliases(struct inode *inode) { + LIST_HEAD(dispose); struct dentry *dentry; -restart: + spin_lock(&inode->i_lock); hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) { spin_lock(&dentry->d_lock); - if (!dentry->d_lockref.count) { - struct dentry *parent = lock_parent(dentry); - if (likely(!dentry->d_lockref.count)) { - __dentry_kill(dentry); - dput(parent); - goto restart; - } - if (parent) - spin_unlock(&parent->d_lock); - } + if (!dentry->d_lockref.count) + to_shrink_list(dentry, &dispose); spin_unlock(&dentry->d_lock); } spin_unlock(&inode->i_lock); + shrink_dentry_list(&dispose); } EXPORT_SYMBOL(d_prune_aliases); -/* - * Lock a dentry from shrink list. - * Called under rcu_read_lock() and dentry->d_lock; the former - * guarantees that nothing we access will be freed under us. - * Note that dentry is *not* protected from concurrent dentry_kill(), - * d_delete(), etc. - * - * Return false if dentry has been disrupted or grabbed, leaving - * the caller to kick it off-list. Otherwise, return true and have - * that dentry's inode and parent both locked. - */ -static bool shrink_lock_dentry(struct dentry *dentry) +static inline void shrink_kill(struct dentry *victim) { - struct inode *inode; - struct dentry *parent; - - if (dentry->d_lockref.count) - return false; - - inode = dentry->d_inode; - if (inode && unlikely(!spin_trylock(&inode->i_lock))) { - spin_unlock(&dentry->d_lock); - spin_lock(&inode->i_lock); - spin_lock(&dentry->d_lock); - if (unlikely(dentry->d_lockref.count)) - goto out; - /* changed inode means that somebody had grabbed it */ - if (unlikely(inode != dentry->d_inode)) - goto out; - } - - parent = dentry->d_parent; - if (IS_ROOT(dentry) || likely(spin_trylock(&parent->d_lock))) - return true; - - spin_unlock(&dentry->d_lock); - spin_lock(&parent->d_lock); - if (unlikely(parent != dentry->d_parent)) { - spin_unlock(&parent->d_lock); - spin_lock(&dentry->d_lock); - goto out; - } - spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); - if (likely(!dentry->d_lockref.count)) - return true; - spin_unlock(&parent->d_lock); -out: - if (inode) - spin_unlock(&inode->i_lock); - return false; + do { + rcu_read_unlock(); + victim = __dentry_kill(victim); + rcu_read_lock(); + } while (victim && lock_for_kill(victim)); + rcu_read_unlock(); + if (victim) + spin_unlock(&victim->d_lock); } void shrink_dentry_list(struct list_head *list) { while (!list_empty(list)) { - struct dentry *dentry, *parent; + struct dentry *dentry; dentry = list_entry(list->prev, struct dentry, d_lru); spin_lock(&dentry->d_lock); rcu_read_lock(); - if (!shrink_lock_dentry(dentry)) { - bool can_free = false; + if (!lock_for_kill(dentry)) { + bool can_free; rcu_read_unlock(); d_shrink_del(dentry); - if (dentry->d_lockref.count < 0) - can_free = dentry->d_flags & DCACHE_MAY_FREE; + can_free = dentry->d_flags & DCACHE_DENTRY_KILLED; spin_unlock(&dentry->d_lock); if (can_free) dentry_free(dentry); continue; } - rcu_read_unlock(); d_shrink_del(dentry); - parent = dentry->d_parent; - if (parent != dentry) - __dput_to_list(parent, list); - __dentry_kill(dentry); + shrink_kill(dentry); } } @@ -1241,7 +1114,7 @@ static enum lru_status dentry_lru_isolate(struct list_head *item, * * This is guaranteed by the fact that all LRU management * functions are intermediated by the LRU API calls like - * list_lru_add and list_lru_del. List movement in this file + * list_lru_add_obj and list_lru_del_obj. List movement in this file * only ever occur through this functions or through callbacks * like this one, that are called from the LRU API. * @@ -1349,8 +1222,7 @@ enum d_walk_ret { static void d_walk(struct dentry *parent, void *data, enum d_walk_ret (*enter)(void *, struct dentry *)) { - struct dentry *this_parent; - struct list_head *next; + struct dentry *this_parent, *dentry; unsigned seq = 0; enum d_walk_ret ret; bool retry = true; @@ -1372,13 +1244,9 @@ again: break; } repeat: - next = this_parent->d_subdirs.next; + dentry = d_first_child(this_parent); resume: - while (next != &this_parent->d_subdirs) { - struct list_head *tmp = next; - struct dentry *dentry = list_entry(tmp, struct dentry, d_child); - next = tmp->next; - + hlist_for_each_entry_from(dentry, d_sib) { if (unlikely(dentry->d_flags & DCACHE_DENTRY_CURSOR)) continue; @@ -1399,7 +1267,7 @@ resume: continue; } - if (!list_empty(&dentry->d_subdirs)) { + if (!hlist_empty(&dentry->d_children)) { spin_unlock(&this_parent->d_lock); spin_release(&dentry->d_lock.dep_map, _RET_IP_); this_parent = dentry; @@ -1414,24 +1282,23 @@ resume: rcu_read_lock(); ascend: if (this_parent != parent) { - struct dentry *child = this_parent; - this_parent = child->d_parent; + dentry = this_parent; + this_parent = dentry->d_parent; - spin_unlock(&child->d_lock); + spin_unlock(&dentry->d_lock); spin_lock(&this_parent->d_lock); /* might go back up the wrong parent if we have had a rename. */ if (need_seqretry(&rename_lock, seq)) goto rename_retry; /* go into the first sibling still alive */ - do { - next = child->d_child.next; - if (next == &this_parent->d_subdirs) - goto ascend; - child = list_entry(next, struct dentry, d_child); - } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)); - rcu_read_unlock(); - goto resume; + hlist_for_each_entry_continue(dentry, d_sib) { + if (likely(!(dentry->d_flags & DCACHE_DENTRY_KILLED))) { + rcu_read_unlock(); + goto resume; + } + } + goto ascend; } if (need_seqretry(&rename_lock, seq)) goto rename_retry; @@ -1531,7 +1398,7 @@ out: * Search the dentry child list of the specified parent, * and move any unused dentries to the end of the unused * list for prune_dcache(). We descend to the next level - * whenever the d_subdirs list is non-empty and continue + * whenever the d_children list is non-empty and continue * searching. * * It returns zero iff there are no unused children, @@ -1561,13 +1428,11 @@ static enum d_walk_ret select_collect(void *_data, struct dentry *dentry) if (dentry->d_flags & DCACHE_SHRINK_LIST) { data->found++; - } else { - if (dentry->d_flags & DCACHE_LRU_LIST) - d_lru_del(dentry); - if (!dentry->d_lockref.count) { - d_shrink_add(dentry, &data->dispose); - data->found++; - } + } else if (!dentry->d_lockref.count) { + to_shrink_list(dentry, &data->dispose); + data->found++; + } else if (dentry->d_lockref.count < 0) { + data->found++; } /* * We can return to the caller if we have found some (this @@ -1588,17 +1453,13 @@ static enum d_walk_ret select_collect2(void *_data, struct dentry *dentry) if (data->start == dentry) goto out; - if (dentry->d_flags & DCACHE_SHRINK_LIST) { - if (!dentry->d_lockref.count) { + if (!dentry->d_lockref.count) { + if (dentry->d_flags & DCACHE_SHRINK_LIST) { rcu_read_lock(); data->victim = dentry; return D_WALK_QUIT; } - } else { - if (dentry->d_flags & DCACHE_LRU_LIST) - d_lru_del(dentry); - if (!dentry->d_lockref.count) - d_shrink_add(dentry, &data->dispose); + to_shrink_list(dentry, &data->dispose); } /* * We can return to the caller if we have found some (this @@ -1636,17 +1497,12 @@ void shrink_dcache_parent(struct dentry *parent) data.victim = NULL; d_walk(parent, &data, select_collect2); if (data.victim) { - struct dentry *parent; spin_lock(&data.victim->d_lock); - if (!shrink_lock_dentry(data.victim)) { + if (!lock_for_kill(data.victim)) { spin_unlock(&data.victim->d_lock); rcu_read_unlock(); } else { - rcu_read_unlock(); - parent = data.victim->d_parent; - if (parent != data.victim) - __dput_to_list(parent, &data.dispose); - __dentry_kill(data.victim); + shrink_kill(data.victim); } } if (!list_empty(&data.dispose)) @@ -1658,7 +1514,7 @@ EXPORT_SYMBOL(shrink_dcache_parent); static enum d_walk_ret umount_check(void *_data, struct dentry *dentry) { /* it has busy descendents; complain about those instead */ - if (!list_empty(&dentry->d_subdirs)) + if (!hlist_empty(&dentry->d_children)) return D_WALK_CONTINUE; /* root with refcount 1 is fine */ @@ -1708,8 +1564,7 @@ static enum d_walk_ret find_submount(void *_data, struct dentry *dentry) { struct dentry **victim = _data; if (d_mountpoint(dentry)) { - __dget_dlock(dentry); - *victim = dentry; + *victim = dget_dlock(dentry); return D_WALK_QUIT; } return D_WALK_CONTINUE; @@ -1815,9 +1670,9 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) dentry->d_fsdata = NULL; INIT_HLIST_BL_NODE(&dentry->d_hash); INIT_LIST_HEAD(&dentry->d_lru); - INIT_LIST_HEAD(&dentry->d_subdirs); + INIT_HLIST_HEAD(&dentry->d_children); INIT_HLIST_NODE(&dentry->d_u.d_alias); - INIT_LIST_HEAD(&dentry->d_child); + INIT_HLIST_NODE(&dentry->d_sib); d_set_d_op(dentry, dentry->d_sb->s_d_op); if (dentry->d_op && dentry->d_op->d_init) { @@ -1854,9 +1709,8 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) * don't need child lock because it is not subject * to concurrency here */ - __dget_dlock(parent); - dentry->d_parent = parent; - list_add(&dentry->d_child, &parent->d_subdirs); + dentry->d_parent = dget_dlock(parent); + hlist_add_head(&dentry->d_sib, &parent->d_children); spin_unlock(&parent->d_lock); return dentry; @@ -1896,9 +1750,15 @@ struct dentry *d_alloc_cursor(struct dentry * parent) */ struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) { + static const struct dentry_operations anon_ops = { + .d_dname = simple_dname + }; struct dentry *dentry = __d_alloc(sb, name); - if (likely(dentry)) + if (likely(dentry)) { dentry->d_flags |= DCACHE_NORCU; + if (!sb->s_d_op) + d_set_d_op(dentry, &anon_ops); + } return dentry; } @@ -1942,22 +1802,6 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) } EXPORT_SYMBOL(d_set_d_op); - -/* - * d_set_fallthru - Mark a dentry as falling through to a lower layer - * @dentry - The dentry to mark - * - * Mark a dentry as falling through to the lower layer (as set with - * d_pin_lower()). This flag may be recorded on the medium. - */ -void d_set_fallthru(struct dentry *dentry) -{ - spin_lock(&dentry->d_lock); - dentry->d_flags |= DCACHE_FALLTHRU; - spin_unlock(&dentry->d_lock); -} -EXPORT_SYMBOL(d_set_fallthru); - static unsigned d_flags_for_inode(struct inode *inode) { unsigned add_flags = DCACHE_REGULAR_TYPE; @@ -2076,75 +1920,55 @@ struct dentry *d_make_root(struct inode *root_inode) } EXPORT_SYMBOL(d_make_root); -static struct dentry *__d_instantiate_anon(struct dentry *dentry, - struct inode *inode, - bool disconnected) -{ - struct dentry *res; - unsigned add_flags; - - security_d_instantiate(dentry, inode); - spin_lock(&inode->i_lock); - res = __d_find_any_alias(inode); - if (res) { - spin_unlock(&inode->i_lock); - dput(dentry); - goto out_iput; - } - - /* attach a disconnected dentry */ - add_flags = d_flags_for_inode(inode); - - if (disconnected) - add_flags |= DCACHE_DISCONNECTED; - - spin_lock(&dentry->d_lock); - __d_set_inode_and_type(dentry, inode, add_flags); - hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry); - if (!disconnected) { - hlist_bl_lock(&dentry->d_sb->s_roots); - hlist_bl_add_head(&dentry->d_hash, &dentry->d_sb->s_roots); - hlist_bl_unlock(&dentry->d_sb->s_roots); - } - spin_unlock(&dentry->d_lock); - spin_unlock(&inode->i_lock); - - return dentry; - - out_iput: - iput(inode); - return res; -} - -struct dentry *d_instantiate_anon(struct dentry *dentry, struct inode *inode) -{ - return __d_instantiate_anon(dentry, inode, true); -} -EXPORT_SYMBOL(d_instantiate_anon); - static struct dentry *__d_obtain_alias(struct inode *inode, bool disconnected) { - struct dentry *tmp; - struct dentry *res; + struct super_block *sb; + struct dentry *new, *res; if (!inode) return ERR_PTR(-ESTALE); if (IS_ERR(inode)) return ERR_CAST(inode); - res = d_find_any_alias(inode); + sb = inode->i_sb; + + res = d_find_any_alias(inode); /* existing alias? */ if (res) - goto out_iput; + goto out; - tmp = d_alloc_anon(inode->i_sb); - if (!tmp) { + new = d_alloc_anon(sb); + if (!new) { res = ERR_PTR(-ENOMEM); - goto out_iput; + goto out; } - return __d_instantiate_anon(tmp, inode, disconnected); + security_d_instantiate(new, inode); + spin_lock(&inode->i_lock); + res = __d_find_any_alias(inode); /* recheck under lock */ + if (likely(!res)) { /* still no alias, attach a disconnected dentry */ + unsigned add_flags = d_flags_for_inode(inode); + + if (disconnected) + add_flags |= DCACHE_DISCONNECTED; + + spin_lock(&new->d_lock); + __d_set_inode_and_type(new, inode, add_flags); + hlist_add_head(&new->d_u.d_alias, &inode->i_dentry); + if (!disconnected) { + hlist_bl_lock(&sb->s_roots); + hlist_bl_add_head(&new->d_hash, &sb->s_roots); + hlist_bl_unlock(&sb->s_roots); + } + spin_unlock(&new->d_lock); + spin_unlock(&inode->i_lock); + inode = NULL; /* consumed by new->d_inode */ + res = new; + } else { + spin_unlock(&inode->i_lock); + dput(new); + } -out_iput: + out: iput(inode); return res; } @@ -2728,7 +2552,7 @@ retry: /* we can't take ->d_lock here; it's OK, though. */ new->d_flags |= DCACHE_PAR_LOOKUP; new->d_wait = wq; - hlist_bl_add_head_rcu(&new->d_u.d_in_lookup_hash, b); + hlist_bl_add_head(&new->d_u.d_in_lookup_hash, b); hlist_bl_unlock(b); return new; mismatch: @@ -2852,7 +2676,7 @@ struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode) spin_unlock(&alias->d_lock); alias = NULL; } else { - __dget_dlock(alias); + dget_dlock(alias); __d_rehash(alias); spin_unlock(&alias->d_lock); } @@ -2994,11 +2818,15 @@ static void __d_move(struct dentry *dentry, struct dentry *target, } else { target->d_parent = old_parent; swap_names(dentry, target); - list_move(&target->d_child, &target->d_parent->d_subdirs); + if (!hlist_unhashed(&target->d_sib)) + __hlist_del(&target->d_sib); + hlist_add_head(&target->d_sib, &target->d_parent->d_children); __d_rehash(target); fsnotify_update_flags(target); } - list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); + if (!hlist_unhashed(&dentry->d_sib)) + __hlist_del(&dentry->d_sib); + hlist_add_head(&dentry->d_sib, &dentry->d_parent->d_children); __d_rehash(dentry); fsnotify_update_flags(dentry); fscrypt_handle_d_move(dentry); @@ -3081,8 +2909,7 @@ struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) * Note: If ever the locking in lock_rename() changes, then please * remember to update this too... */ -static int __d_unalias(struct inode *inode, - struct dentry *dentry, struct dentry *alias) +static int __d_unalias(struct dentry *dentry, struct dentry *alias) { struct mutex *m1 = NULL; struct rw_semaphore *m2 = NULL; @@ -3163,7 +2990,7 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) inode->i_sb->s_id); } else if (!IS_ROOT(new)) { struct dentry *old_parent = dget(new->d_parent); - int err = __d_unalias(inode, dentry, new); + int err = __d_unalias(dentry, new); write_sequnlock(&rename_lock); if (err) { dput(new); -- cgit v1.2.3