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Subject[PATCH 1/2] fs/aio.c: Trivially cleanup aio code.
Date
I was interested in how async IO was implemented in Linux. While reading through
it, I noticed a bunch of style problems reported by checkpath.

This patch cleans it up.

Signed-off-by: Emilio Cobos Álvarez <emilio@crisal.io>
---
fs/aio.c | 116 ++++++++++++++++++++++++++++++++++++---------------------------
1 file changed, 66 insertions(+), 50 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index f52d925ee259..be0ca6d9a6b3 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -50,16 +50,16 @@
#define AIO_RING_COMPAT_FEATURES 1
#define AIO_RING_INCOMPAT_FEATURES 0
struct aio_ring {
- unsigned id; /* kernel internal index number */
- unsigned nr; /* number of io_events */
- unsigned head; /* Written to by userland or under ring_lock
+ unsigned int id; /* kernel internal index number */
+ unsigned int nr; /* number of io_events */
+ unsigned int head; /* Written to by userland or under ring_lock
* mutex by aio_read_events_ring(). */
- unsigned tail;
+ unsigned int tail;

- unsigned magic;
- unsigned compat_features;
- unsigned incompat_features;
- unsigned header_length; /* size of aio_ring */
+ unsigned int magic;
+ unsigned int compat_features;
+ unsigned int incompat_features;
+ unsigned int header_length; /* size of aio_ring */


struct io_event io_events[0];
@@ -69,12 +69,12 @@ struct aio_ring {

struct kioctx_table {
struct rcu_head rcu;
- unsigned nr;
+ unsigned int nr;
struct kioctx *table[];
};

struct kioctx_cpu {
- unsigned reqs_available;
+ unsigned int reqs_available;
};

struct ctx_rq_wait {
@@ -96,7 +96,7 @@ struct kioctx {
* For percpu reqs_available, number of slots we move to/from global
* counter at a time:
*/
- unsigned req_batch;
+ unsigned int req_batch;
/*
* This is what userspace passed to io_setup(), it's not used for
* anything but counting against the global max_reqs quota.
@@ -104,10 +104,10 @@ struct kioctx {
* The real limit is nr_events - 1, which will be larger (see
* aio_setup_ring())
*/
- unsigned max_reqs;
+ unsigned int max_reqs;

/* Size of ringbuffer, in units of struct io_event */
- unsigned nr_events;
+ unsigned int nr_events;

unsigned long mmap_base;
unsigned long mmap_size;
@@ -145,15 +145,15 @@ struct kioctx {
} ____cacheline_aligned_in_smp;

struct {
- unsigned tail;
- unsigned completed_events;
+ unsigned int tail;
+ unsigned int completed_events;
spinlock_t completion_lock;
} ____cacheline_aligned_in_smp;

struct page *internal_pages[AIO_RING_PAGES];
struct file *aio_ring_file;

- unsigned id;
+ unsigned int id;
};

/*
@@ -189,9 +189,15 @@ struct aio_kiocb {
};

/*------ sysctl variables----*/
+
static DEFINE_SPINLOCK(aio_nr_lock);
-unsigned long aio_nr; /* current system wide number of aio requests */
-unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
+
+/* current system wide number of aio requests */
+unsigned long aio_nr;
+
+/* system wide maximum number of aio requests */
+unsigned long aio_max_nr = 0x10000;
+
/*----end sysctl variables---*/

static struct kmem_cache *kiocb_cachep;
@@ -208,6 +214,7 @@ static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
struct file *file;
struct path path;
struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
+
if (IS_ERR(inode))
return ERR_CAST(inode);

@@ -263,13 +270,13 @@ static int __init aio_setup(void)
panic("Failed to create aio fs mount.");

kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
- kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
+ kioctx_cachep = KMEM_CACHE(kioctx, SLAB_HWCACHE_ALIGN|SLAB_PANIC);

pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));

return 0;
}
-__initcall(aio_setup);
+device_initcall(aio_setup);

static void put_aio_ring_file(struct kioctx *ctx)
{
@@ -301,6 +308,7 @@ static void aio_free_ring(struct kioctx *ctx)

for (i = 0; i < ctx->nr_pages; i++) {
struct page *page;
+
pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
page_count(ctx->ring_pages[i]));
page = ctx->ring_pages[i];
@@ -444,7 +452,7 @@ static const struct address_space_operations aio_ctx_aops = {
static int aio_setup_ring(struct kioctx *ctx)
{
struct aio_ring *ring;
- unsigned nr_events = ctx->max_reqs;
+ unsigned int nr_events = ctx->max_reqs;
struct mm_struct *mm = current->mm;
unsigned long size, unused;
int nr_pages;
@@ -483,6 +491,7 @@ static int aio_setup_ring(struct kioctx *ctx)

for (i = 0; i < nr_pages; i++) {
struct page *page;
+
page = find_or_create_page(file->f_mapping,
i, GFP_HIGHUSER | __GFP_ZERO);
if (!page)
@@ -634,7 +643,7 @@ static void free_ioctx_users(struct percpu_ref *ref)

static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
{
- unsigned i, new_nr;
+ unsigned int i, new_nr;
struct kioctx_table *table, *old;
struct aio_ring *ring;

@@ -687,7 +696,7 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
}
}

-static void aio_nr_sub(unsigned nr)
+static void aio_nr_sub(unsigned int nr)
{
spin_lock(&aio_nr_lock);
if (WARN_ON(aio_nr - nr > aio_nr))
@@ -700,7 +709,7 @@ static void aio_nr_sub(unsigned nr)
/* ioctx_alloc
* Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
*/
-static struct kioctx *ioctx_alloc(unsigned nr_events)
+static struct kioctx *ioctx_alloc(unsigned int nr_events)
{
struct mm_struct *mm = current->mm;
struct kioctx *ctx;
@@ -736,8 +745,10 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
spin_lock_init(&ctx->ctx_lock);
spin_lock_init(&ctx->completion_lock);
mutex_init(&ctx->ring_lock);
- /* Protect against page migration throughout kiotx setup by keeping
- * the ring_lock mutex held until setup is complete. */
+ /*
+ * Protect against page migration throughout kiotx setup by keeping
+ * the ring_lock mutex held until setup is complete.
+ */
mutex_lock(&ctx->ring_lock);
init_waitqueue_head(&ctx->wait);

@@ -894,7 +905,7 @@ void exit_aio(struct mm_struct *mm)
kfree(table);
}

-static void put_reqs_available(struct kioctx *ctx, unsigned nr)
+static void put_reqs_available(struct kioctx *ctx, unsigned int nr)
{
struct kioctx_cpu *kcpu;
unsigned long flags;
@@ -948,10 +959,10 @@ static bool get_reqs_available(struct kioctx *ctx)
* from aio_get_req() (the we're out of events case). It must be
* called holding ctx->completion_lock.
*/
-static void refill_reqs_available(struct kioctx *ctx, unsigned head,
- unsigned tail)
+static void refill_reqs_available(struct kioctx *ctx, unsigned int head,
+ unsigned int tail)
{
- unsigned events_in_ring, completed;
+ unsigned int events_in_ring, completed;

/* Clamp head since userland can write to it. */
head %= ctx->nr_events;
@@ -982,7 +993,7 @@ static void user_refill_reqs_available(struct kioctx *ctx)
spin_lock_irq(&ctx->completion_lock);
if (ctx->completed_events) {
struct aio_ring *ring;
- unsigned head;
+ unsigned int head;

/* Access of ring->head may race with aio_read_events_ring()
* here, but that's okay since whether we read the old version
@@ -1045,7 +1056,7 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id)
struct mm_struct *mm = current->mm;
struct kioctx *ctx, *ret = NULL;
struct kioctx_table *table;
- unsigned id;
+ unsigned int id;

if (get_user(id, &ring->id))
return NULL;
@@ -1075,7 +1086,7 @@ static void aio_complete(struct kiocb *kiocb, long res, long res2)
struct kioctx *ctx = iocb->ki_ctx;
struct aio_ring *ring;
struct io_event *ev_page, *event;
- unsigned tail, pos, head;
+ unsigned int tail, pos, head;
unsigned long flags;

if (kiocb->ki_flags & IOCB_WRITE) {
@@ -1085,8 +1096,10 @@ static void aio_complete(struct kiocb *kiocb, long res, long res2)
* Tell lockdep we inherited freeze protection from submission
* thread.
*/
- if (S_ISREG(file_inode(file)->i_mode))
- __sb_writers_acquired(file_inode(file)->i_sb, SB_FREEZE_WRITE);
+ if (S_ISREG(file_inode(file)->i_mode)) {
+ __sb_writers_acquired(file_inode(file)->i_sb,
+ SB_FREEZE_WRITE);
+ }
file_end_write(file);
}

@@ -1131,7 +1144,7 @@ static void aio_complete(struct kiocb *kiocb, long res, long res2)
kunmap_atomic(ev_page);
flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);

- pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
+ pr_debug("%p[%u]: %p: %p %llx %lx %lx\n",
ctx, tail, iocb, iocb->ki_user_iocb, iocb->ki_user_data,
res, res2);

@@ -1188,7 +1201,7 @@ static long aio_read_events_ring(struct kioctx *ctx,
struct io_event __user *event, long nr)
{
struct aio_ring *ring;
- unsigned head, tail, pos;
+ unsigned int head, tail, pos;
long ret = 0;
int copy_ret;

@@ -1329,16 +1342,16 @@ static long read_events(struct kioctx *ctx, long min_nr, long nr,
* Create an aio_context capable of receiving at least nr_events.
* ctxp must not point to an aio_context that already exists, and
* must be initialized to 0 prior to the call. On successful
- * creation of the aio_context, *ctxp is filled in with the resulting
+ * creation of the aio_context, *ctxp is filled in with the resulting
* handle. May fail with -EINVAL if *ctxp is not initialized,
- * if the specified nr_events exceeds internal limits. May fail
- * with -EAGAIN if the specified nr_events exceeds the user's limit
+ * if the specified nr_events exceeds internal limits. May fail
+ * with -EAGAIN if the specified nr_events exceeds the user's limit
* of available events. May fail with -ENOMEM if insufficient kernel
* resources are available. May fail with -EFAULT if an invalid
* pointer is passed for ctxp. Will fail with -ENOSYS if not
* implemented.
*/
-SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
+SYSCALL_DEFINE2(io_setup, unsigned int, nr_events, aio_context_t __user *, ctxp)
{
struct kioctx *ioctx = NULL;
unsigned long ctx;
@@ -1351,7 +1364,7 @@ SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
ret = -EINVAL;
if (unlikely(ctx || nr_events == 0)) {
pr_debug("EINVAL: ctx %lu nr_events %u\n",
- ctx, nr_events);
+ ctx, nr_events);
goto out;
}

@@ -1369,7 +1382,7 @@ SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
}

#ifdef CONFIG_COMPAT
-COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
+COMPAT_SYSCALL_DEFINE2(io_setup, unsigned int, nr_events, u32 __user *, ctx32p)
{
struct kioctx *ioctx = NULL;
unsigned long ctx;
@@ -1382,7 +1395,7 @@ COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
ret = -EINVAL;
if (unlikely(ctx || nr_events == 0)) {
pr_debug("EINVAL: ctx %lu nr_events %u\n",
- ctx, nr_events);
+ ctx, nr_events);
goto out;
}

@@ -1402,7 +1415,7 @@ COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
#endif

/* sys_io_destroy:
- * Destroy the aio_context specified. May cancel any outstanding
+ * Destroy the aio_context specified. May cancel any outstanding
* AIOs and block on completion. Will fail with -ENOSYS if not
* implemented. May fail with -EINVAL if the context pointed to
* is invalid.
@@ -1410,7 +1423,8 @@ COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
{
struct kioctx *ioctx = lookup_ioctx(ctx);
- if (likely(NULL != ioctx)) {
+
+ if (likely(ioctx)) {
struct ctx_rq_wait wait;
int ret;

@@ -1526,8 +1540,10 @@ static ssize_t aio_write(struct kiocb *req, struct iocb *iocb, bool vectored,
* by telling it the lock got released so that it doesn't
* complain about held lock when we return to userspace.
*/
- if (S_ISREG(file_inode(file)->i_mode))
- __sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
+ if (S_ISREG(file_inode(file)->i_mode)) {
+ __sb_writers_release(file_inode(file)->i_sb,
+ SB_FREEZE_WRITE);
+ }
}
kfree(iovec);
return ret;
@@ -1655,7 +1671,7 @@ static long do_io_submit(aio_context_t ctx_id, long nr,
* AKPM: should this return a partial result if some of the IOs were
* successfully submitted?
*/
- for (i=0; i<nr; i++) {
+ for (i = 0; i < nr; i++) {
struct iocb __user *user_iocb;
struct iocb tmp;

@@ -1713,7 +1729,7 @@ copy_iocb(long nr, u32 __user *ptr32, struct iocb __user * __user *ptr64)
return 0;
}

-#define MAX_AIO_SUBMITS (PAGE_SIZE/sizeof(struct iocb *))
+#define MAX_AIO_SUBMITS (PAGE_SIZE/sizeof(struct iocb *))

COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
int, nr, u32 __user *, iocb)
--
2.12.1
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