diff options
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/eventpoll.c | 2 | ||||
| -rw-r--r-- | fs/file.c | 77 | ||||
| -rw-r--r-- | fs/file_table.c | 49 |
3 files changed, 108 insertions, 20 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 1ae4542f0bd8..212383cefe6c 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1002,7 +1002,7 @@ static struct file *epi_fget(const struct epitem *epi) struct file *file; file = epi->ffd.file; - if (!atomic_long_inc_not_zero(&file->f_count)) + if (!file_ref_get(&file->f_ref)) file = NULL; return file; } diff --git a/fs/file.c b/fs/file.c index 7251d215048d..efd9959b03c2 100644 --- a/fs/file.c +++ b/fs/file.c @@ -20,10 +20,73 @@ #include <linux/spinlock.h> #include <linux/rcupdate.h> #include <linux/close_range.h> +#include <linux/file_ref.h> #include <net/sock.h> #include "internal.h" +/** + * __file_ref_put - Slowpath of file_ref_put() + * @ref: Pointer to the reference count + * @cnt: Current reference count + * + * Invoked when the reference count is outside of the valid zone. + * + * Return: + * True if this was the last reference with no future references + * possible. This signals the caller that it can safely schedule the + * object, which is protected by the reference counter, for + * deconstruction. + * + * False if there are still active references or the put() raced + * with a concurrent get()/put() pair. Caller is not allowed to + * deconstruct the protected object. + */ +bool __file_ref_put(file_ref_t *ref, unsigned long cnt) +{ + /* Did this drop the last reference? */ + if (likely(cnt == FILE_REF_NOREF)) { + /* + * Carefully try to set the reference count to FILE_REF_DEAD. + * + * This can fail if a concurrent get() operation has + * elevated it again or the corresponding put() even marked + * it dead already. Both are valid situations and do not + * require a retry. If this fails the caller is not + * allowed to deconstruct the object. + */ + if (!atomic_long_try_cmpxchg_release(&ref->refcnt, &cnt, FILE_REF_DEAD)) + return false; + + /* + * The caller can safely schedule the object for + * deconstruction. Provide acquire ordering. + */ + smp_acquire__after_ctrl_dep(); + return true; + } + + /* + * If the reference count was already in the dead zone, then this + * put() operation is imbalanced. Warn, put the reference count back to + * DEAD and tell the caller to not deconstruct the object. + */ + if (WARN_ONCE(cnt >= FILE_REF_RELEASED, "imbalanced put on file reference count")) { + atomic_long_set(&ref->refcnt, FILE_REF_DEAD); + return false; + } + + /* + * This is a put() operation on a saturated refcount. Restore the + * mean saturation value and tell the caller to not deconstruct the + * object. + */ + if (cnt > FILE_REF_MAXREF) + atomic_long_set(&ref->refcnt, FILE_REF_SATURATED); + return false; +} +EXPORT_SYMBOL_GPL(__file_ref_put); + unsigned int sysctl_nr_open __read_mostly = 1024*1024; unsigned int sysctl_nr_open_min = BITS_PER_LONG; /* our min() is unusable in constant expressions ;-/ */ @@ -820,7 +883,7 @@ static struct file *__get_file_rcu(struct file __rcu **f) if (!file) return NULL; - if (unlikely(!atomic_long_inc_not_zero(&file->f_count))) + if (unlikely(!file_ref_get(&file->f_ref))) return ERR_PTR(-EAGAIN); file_reloaded = rcu_dereference_raw(*f); @@ -834,8 +897,8 @@ static struct file *__get_file_rcu(struct file __rcu **f) OPTIMIZER_HIDE_VAR(file_reloaded_cmp); /* - * atomic_long_inc_not_zero() above provided a full memory - * barrier when we acquired a reference. + * file_ref_get() above provided a full memory barrier when we + * acquired a reference. * * This is paired with the write barrier from assigning to the * __rcu protected file pointer so that if that pointer still @@ -933,11 +996,11 @@ static inline struct file *__fget_files_rcu(struct files_struct *files, * We need to confirm it by incrementing the refcount * and then check the lookup again. * - * atomic_long_inc_not_zero() gives us a full memory - * barrier. We only really need an 'acquire' one to - * protect the loads below, but we don't have that. + * file_ref_get() gives us a full memory barrier. We + * only really need an 'acquire' one to protect the + * loads below, but we don't have that. */ - if (unlikely(!atomic_long_inc_not_zero(&file->f_count))) + if (unlikely(!file_ref_get(&file->f_ref))) continue; /* diff --git a/fs/file_table.c b/fs/file_table.c index 9e46fd4336b0..976736be47cb 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -39,13 +39,17 @@ static struct files_stat_struct files_stat = { /* SLAB cache for file structures */ static struct kmem_cache *filp_cachep __ro_after_init; +static struct kmem_cache *bfilp_cachep __ro_after_init; static struct percpu_counter nr_files __cacheline_aligned_in_smp; /* Container for backing file with optional user path */ struct backing_file { struct file file; - struct path user_path; + union { + struct path user_path; + freeptr_t bf_freeptr; + }; }; static inline struct backing_file *backing_file(struct file *f) @@ -67,7 +71,7 @@ static inline void file_free(struct file *f) put_cred(f->f_cred); if (unlikely(f->f_mode & FMODE_BACKING)) { path_put(backing_file_user_path(f)); - kfree(backing_file(f)); + kmem_cache_free(bfilp_cachep, backing_file(f)); } else { kmem_cache_free(filp_cachep, f); } @@ -164,16 +168,32 @@ static int init_file(struct file *f, int flags, const struct cred *cred) * the respective member when opening the file. */ mutex_init(&f->f_pos_lock); - f->f_flags = flags; - f->f_mode = OPEN_FMODE(flags); - /* f->f_version: 0 */ + memset(&f->f_path, 0, sizeof(f->f_path)); + memset(&f->f_ra, 0, sizeof(f->f_ra)); + + f->f_flags = flags; + f->f_mode = OPEN_FMODE(flags); + + f->f_op = NULL; + f->f_mapping = NULL; + f->private_data = NULL; + f->f_inode = NULL; + f->f_owner = NULL; +#ifdef CONFIG_EPOLL + f->f_ep = NULL; +#endif + + f->f_iocb_flags = 0; + f->f_pos = 0; + f->f_wb_err = 0; + f->f_sb_err = 0; /* * We're SLAB_TYPESAFE_BY_RCU so initialize f_count last. While * fget-rcu pattern users need to be able to handle spurious * refcount bumps we should reinitialize the reused file first. */ - atomic_long_set(&f->f_count, 1); + file_ref_init(&f->f_ref, 1); return 0; } @@ -205,7 +225,7 @@ struct file *alloc_empty_file(int flags, const struct cred *cred) goto over; } - f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL); + f = kmem_cache_alloc(filp_cachep, GFP_KERNEL); if (unlikely(!f)) return ERR_PTR(-ENOMEM); @@ -239,7 +259,7 @@ struct file *alloc_empty_file_noaccount(int flags, const struct cred *cred) struct file *f; int error; - f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL); + f = kmem_cache_alloc(filp_cachep, GFP_KERNEL); if (unlikely(!f)) return ERR_PTR(-ENOMEM); @@ -266,13 +286,13 @@ struct file *alloc_empty_backing_file(int flags, const struct cred *cred) struct backing_file *ff; int error; - ff = kzalloc(sizeof(struct backing_file), GFP_KERNEL); + ff = kmem_cache_alloc(bfilp_cachep, GFP_KERNEL); if (unlikely(!ff)) return ERR_PTR(-ENOMEM); error = init_file(&ff->file, flags, cred); if (unlikely(error)) { - kfree(ff); + kmem_cache_free(bfilp_cachep, ff); return ERR_PTR(error); } @@ -478,7 +498,7 @@ static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput); void fput(struct file *file) { - if (atomic_long_dec_and_test(&file->f_count)) { + if (file_ref_put(&file->f_ref)) { struct task_struct *task = current; if (unlikely(!(file->f_mode & (FMODE_BACKING | FMODE_OPENED)))) { @@ -511,7 +531,7 @@ void fput(struct file *file) */ void __fput_sync(struct file *file) { - if (atomic_long_dec_and_test(&file->f_count)) + if (file_ref_put(&file->f_ref)) __fput(file); } @@ -528,6 +548,11 @@ void __init files_init(void) filp_cachep = kmem_cache_create("filp", sizeof(struct file), &args, SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU); + + args.freeptr_offset = offsetof(struct backing_file, bf_freeptr); + bfilp_cachep = kmem_cache_create("bfilp", sizeof(struct backing_file), + &args, SLAB_HWCACHE_ALIGN | SLAB_PANIC | + SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU); percpu_counter_init(&nr_files, 0, GFP_KERNEL); } |