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author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-07-28 12:59:05 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-07-28 12:59:05 -0700 |
commit | 6784725ab0b9473ce44bfad91a256bd72b5cddc1 (patch) | |
tree | f31e2bfc4795c2ee490b0eb9fb752be58060568f /fs/dcache.c | |
parent | 554828ee0db41618d101d9549db8808af9fd9d65 (diff) | |
parent | 47be61845c775643f1aa4d2a54343549f943c94c (diff) | |
download | op-kernel-dev-6784725ab0b9473ce44bfad91a256bd72b5cddc1.zip op-kernel-dev-6784725ab0b9473ce44bfad91a256bd72b5cddc1.tar.gz |
Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs updates from Al Viro:
"Assorted cleanups and fixes.
Probably the most interesting part long-term is ->d_init() - that will
have a bunch of followups in (at least) ceph and lustre, but we'll
need to sort the barrier-related rules before it can get used for
really non-trivial stuff.
Another fun thing is the merge of ->d_iput() callers (dentry_iput()
and dentry_unlink_inode()) and a bunch of ->d_compare() ones (all
except the one in __d_lookup_lru())"
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (26 commits)
fs/dcache.c: avoid soft-lockup in dput()
vfs: new d_init method
vfs: Update lookup_dcache() comment
bdev: get rid of ->bd_inodes
Remove last traces of ->sync_page
new helper: d_same_name()
dentry_cmp(): use lockless_dereference() instead of smp_read_barrier_depends()
vfs: clean up documentation
vfs: document ->d_real()
vfs: merge .d_select_inode() into .d_real()
unify dentry_iput() and dentry_unlink_inode()
binfmt_misc: ->s_root is not going anywhere
drop redundant ->owner initializations
ufs: get rid of redundant checks
orangefs: constify inode_operations
missed comment updates from ->direct_IO() prototype change
file_inode(f)->i_mapping is f->f_mapping
trim fsnotify hooks a bit
9p: new helper - v9fs_parent_fid()
debugfs: ->d_parent is never NULL or negative
...
Diffstat (limited to 'fs/dcache.c')
-rw-r--r-- | fs/dcache.c | 208 |
1 files changed, 69 insertions, 139 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 24bf27d..b90cf8e 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -224,10 +224,9 @@ static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount) { - const unsigned char *cs; /* * Be careful about RCU walk racing with rename: - * use ACCESS_ONCE to fetch the name pointer. + * use 'lockless_dereference' to fetch the name pointer. * * NOTE! Even if a rename will mean that the length * was not loaded atomically, we don't care. The @@ -241,8 +240,8 @@ static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *c * early because the data cannot match (there can * be no NUL in the ct/tcount data) */ - cs = ACCESS_ONCE(dentry->d_name.name); - smp_read_barrier_depends(); + const unsigned char *cs = lockless_dereference(dentry->d_name.name); + return dentry_string_cmp(cs, ct, tcount); } @@ -333,44 +332,21 @@ static inline void dentry_rcuwalk_invalidate(struct dentry *dentry) /* * Release the dentry's inode, using the filesystem - * d_iput() operation if defined. Dentry has no refcount - * and is unhashed. - */ -static void dentry_iput(struct dentry * dentry) - __releases(dentry->d_lock) - __releases(dentry->d_inode->i_lock) -{ - struct inode *inode = dentry->d_inode; - if (inode) { - __d_clear_type_and_inode(dentry); - hlist_del_init(&dentry->d_u.d_alias); - spin_unlock(&dentry->d_lock); - spin_unlock(&inode->i_lock); - if (!inode->i_nlink) - fsnotify_inoderemove(inode); - if (dentry->d_op && dentry->d_op->d_iput) - dentry->d_op->d_iput(dentry, inode); - else - iput(inode); - } else { - spin_unlock(&dentry->d_lock); - } -} - -/* - * Release the dentry's inode, using the filesystem - * d_iput() operation if defined. dentry remains in-use. + * d_iput() operation if defined. */ static void dentry_unlink_inode(struct dentry * dentry) __releases(dentry->d_lock) __releases(dentry->d_inode->i_lock) { struct inode *inode = dentry->d_inode; + bool hashed = !d_unhashed(dentry); - raw_write_seqcount_begin(&dentry->d_seq); + if (hashed) + raw_write_seqcount_begin(&dentry->d_seq); __d_clear_type_and_inode(dentry); hlist_del_init(&dentry->d_u.d_alias); - raw_write_seqcount_end(&dentry->d_seq); + if (hashed) + raw_write_seqcount_end(&dentry->d_seq); spin_unlock(&dentry->d_lock); spin_unlock(&inode->i_lock); if (!inode->i_nlink) @@ -571,12 +547,10 @@ static void __dentry_kill(struct dentry *dentry) dentry_unlist(dentry, parent); if (parent) spin_unlock(&parent->d_lock); - dentry_iput(dentry); - /* - * dentry_iput drops the locks, at which point nobody (except - * transient RCU lookups) can reach this dentry. - */ - BUG_ON(dentry->d_lockref.count > 0); + if (dentry->d_inode) + dentry_unlink_inode(dentry); + else + spin_unlock(&dentry->d_lock); this_cpu_dec(nr_dentry); if (dentry->d_op && dentry->d_op->d_release) dentry->d_op->d_release(dentry); @@ -620,7 +594,6 @@ static struct dentry *dentry_kill(struct dentry *dentry) failed: spin_unlock(&dentry->d_lock); - cpu_relax(); return dentry; /* try again with same dentry */ } @@ -794,6 +767,8 @@ void dput(struct dentry *dentry) return; repeat: + might_sleep(); + rcu_read_lock(); if (likely(fast_dput(dentry))) { rcu_read_unlock(); @@ -827,8 +802,10 @@ repeat: kill_it: dentry = dentry_kill(dentry); - if (dentry) + if (dentry) { + cond_resched(); goto repeat; + } } EXPORT_SYMBOL(dput); @@ -1593,6 +1570,7 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) { struct dentry *dentry; char *dname; + int err; dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); if (!dentry) @@ -1651,6 +1629,16 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) INIT_LIST_HEAD(&dentry->d_child); d_set_d_op(dentry, dentry->d_sb->s_d_op); + if (dentry->d_op && dentry->d_op->d_init) { + err = dentry->d_op->d_init(dentry); + if (err) { + if (dname_external(dentry)) + kfree(external_name(dentry)); + kmem_cache_free(dentry_cache, dentry); + return NULL; + } + } + this_cpu_inc(nr_dentry); return dentry; @@ -1727,7 +1715,6 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | DCACHE_OP_DELETE | - DCACHE_OP_SELECT_INODE | DCACHE_OP_REAL)); dentry->d_op = op; if (!op) @@ -1744,8 +1731,6 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) dentry->d_flags |= DCACHE_OP_DELETE; if (op->d_prune) dentry->d_flags |= DCACHE_OP_PRUNE; - if (op->d_select_inode) - dentry->d_flags |= DCACHE_OP_SELECT_INODE; if (op->d_real) dentry->d_flags |= DCACHE_OP_REAL; @@ -1813,7 +1798,7 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode) raw_write_seqcount_begin(&dentry->d_seq); __d_set_inode_and_type(dentry, inode, add_flags); raw_write_seqcount_end(&dentry->d_seq); - __fsnotify_d_instantiate(dentry); + fsnotify_update_flags(dentry); spin_unlock(&dentry->d_lock); } @@ -2065,42 +2050,19 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, } EXPORT_SYMBOL(d_add_ci); -/* - * Do the slow-case of the dentry name compare. - * - * Unlike the dentry_cmp() function, we need to atomically - * load the name and length information, so that the - * filesystem can rely on them, and can use the 'name' and - * 'len' information without worrying about walking off the - * end of memory etc. - * - * Thus the read_seqcount_retry() and the "duplicate" info - * in arguments (the low-level filesystem should not look - * at the dentry inode or name contents directly, since - * rename can change them while we're in RCU mode). - */ -enum slow_d_compare { - D_COMP_OK, - D_COMP_NOMATCH, - D_COMP_SEQRETRY, -}; -static noinline enum slow_d_compare slow_dentry_cmp( - const struct dentry *parent, - struct dentry *dentry, - unsigned int seq, - const struct qstr *name) +static inline bool d_same_name(const struct dentry *dentry, + const struct dentry *parent, + const struct qstr *name) { - int tlen = dentry->d_name.len; - const char *tname = dentry->d_name.name; - - if (read_seqcount_retry(&dentry->d_seq, seq)) { - cpu_relax(); - return D_COMP_SEQRETRY; + if (likely(!(parent->d_flags & DCACHE_OP_COMPARE))) { + if (dentry->d_name.len != name->len) + return false; + return dentry_cmp(dentry, name->name, name->len) == 0; } - if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) - return D_COMP_NOMATCH; - return D_COMP_OK; + return parent->d_op->d_compare(parent, dentry, + dentry->d_name.len, dentry->d_name.name, + name) == 0; } /** @@ -2179,6 +2141,9 @@ seqretry: * dentry compare, we will do seqretries until it is stable, * and if we end up with a successful lookup, we actually * want to exit RCU lookup anyway. + * + * Note that raw_seqcount_begin still *does* smp_rmb(), so + * we are still guaranteed NUL-termination of ->d_name.name. */ seq = raw_seqcount_begin(&dentry->d_seq); if (dentry->d_parent != parent) @@ -2187,24 +2152,28 @@ seqretry: continue; if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { + int tlen; + const char *tname; if (dentry->d_name.hash != hashlen_hash(hashlen)) continue; - *seqp = seq; - switch (slow_dentry_cmp(parent, dentry, seq, name)) { - case D_COMP_OK: - return dentry; - case D_COMP_NOMATCH: - continue; - default: + tlen = dentry->d_name.len; + tname = dentry->d_name.name; + /* we want a consistent (name,len) pair */ + if (read_seqcount_retry(&dentry->d_seq, seq)) { + cpu_relax(); goto seqretry; } + if (parent->d_op->d_compare(parent, dentry, + tlen, tname, name) != 0) + continue; + } else { + if (dentry->d_name.hash_len != hashlen) + continue; + if (dentry_cmp(dentry, str, hashlen_len(hashlen)) != 0) + continue; } - - if (dentry->d_name.hash_len != hashlen) - continue; *seqp = seq; - if (!dentry_cmp(dentry, str, hashlen_len(hashlen))) - return dentry; + return dentry; } return NULL; } @@ -2252,9 +2221,7 @@ EXPORT_SYMBOL(d_lookup); */ struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) { - unsigned int len = name->len; unsigned int hash = name->hash; - const unsigned char *str = name->name; struct hlist_bl_head *b = d_hash(hash); struct hlist_bl_node *node; struct dentry *found = NULL; @@ -2293,21 +2260,8 @@ struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) if (d_unhashed(dentry)) goto next; - /* - * It is safe to compare names since d_move() cannot - * change the qstr (protected by d_lock). - */ - if (parent->d_flags & DCACHE_OP_COMPARE) { - int tlen = dentry->d_name.len; - const char *tname = dentry->d_name.name; - if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) - goto next; - } else { - if (dentry->d_name.len != len) - goto next; - if (dentry_cmp(dentry, str, len)) - goto next; - } + if (!d_same_name(dentry, parent, name)) + goto next; dentry->d_lockref.count++; found = dentry; @@ -2460,9 +2414,7 @@ struct dentry *d_alloc_parallel(struct dentry *parent, const struct qstr *name, wait_queue_head_t *wq) { - unsigned int len = name->len; unsigned int hash = name->hash; - const unsigned char *str = name->name; struct hlist_bl_head *b = in_lookup_hash(parent, hash); struct hlist_bl_node *node; struct dentry *new = d_alloc(parent, name); @@ -2513,17 +2465,8 @@ retry: continue; if (dentry->d_parent != parent) continue; - if (parent->d_flags & DCACHE_OP_COMPARE) { - int tlen = dentry->d_name.len; - const char *tname = dentry->d_name.name; - if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) - continue; - } else { - if (dentry->d_name.len != len) - continue; - if (dentry_cmp(dentry, str, len)) - continue; - } + if (!d_same_name(dentry, parent, name)) + continue; hlist_bl_unlock(b); /* now we can try to grab a reference */ if (!lockref_get_not_dead(&dentry->d_lockref)) { @@ -2550,17 +2493,8 @@ retry: goto mismatch; if (unlikely(d_unhashed(dentry))) goto mismatch; - if (parent->d_flags & DCACHE_OP_COMPARE) { - int tlen = dentry->d_name.len; - const char *tname = dentry->d_name.name; - if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) - goto mismatch; - } else { - if (unlikely(dentry->d_name.len != len)) - goto mismatch; - if (unlikely(dentry_cmp(dentry, str, len))) - goto mismatch; - } + if (unlikely(!d_same_name(dentry, parent, name))) + goto mismatch; /* OK, it *is* a hashed match; return it */ spin_unlock(&dentry->d_lock); dput(new); @@ -2613,7 +2547,7 @@ static inline void __d_add(struct dentry *dentry, struct inode *inode) raw_write_seqcount_begin(&dentry->d_seq); __d_set_inode_and_type(dentry, inode, add_flags); raw_write_seqcount_end(&dentry->d_seq); - __fsnotify_d_instantiate(dentry); + fsnotify_update_flags(dentry); } _d_rehash(dentry); if (dir) @@ -2656,8 +2590,6 @@ EXPORT_SYMBOL(d_add); struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode) { struct dentry *alias; - int len = entry->d_name.len; - const char *name = entry->d_name.name; unsigned int hash = entry->d_name.hash; spin_lock(&inode->i_lock); @@ -2671,9 +2603,7 @@ struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode) continue; if (alias->d_parent != entry->d_parent) continue; - if (alias->d_name.len != len) - continue; - if (dentry_cmp(alias, name, len)) + if (!d_same_name(alias, entry->d_parent, &entry->d_name)) continue; spin_lock(&alias->d_lock); if (!d_unhashed(alias)) { @@ -2903,8 +2833,8 @@ static void __d_move(struct dentry *dentry, struct dentry *target, list_move(&target->d_child, &target->d_parent->d_subdirs); list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); if (exchange) - fsnotify_d_move(target); - fsnotify_d_move(dentry); + fsnotify_update_flags(target); + fsnotify_update_flags(dentry); } write_seqcount_end(&target->d_seq); |