[PATCH 26/26] Apply fire to dio code

Kent Overstreet
2013-06-09T02:20:51Z

Near total rewrite of fs/direct-io.c. This makes use of our new bio
splitting functionality, and the fact that generic_make_request() will
take arbitrary size bios - we allocate a bio, pin pages to it directly,
then call the getblocks() function to map it wherever the filesystem
tells us - splitting as needed.

This version will break btrfs - we need to add a new kind of hook so
btrfs can do what it wants to more sanely that previously.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
---
fs/direct-io.c | 1318 ++++++++++++++------------------------------------------
1 file changed, 331 insertions(+), 987 deletions(-)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 6a5de20..3c32bf3 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -8,7 +8,7 @@
* 04Jul2002 Andrew Morton
* Initial version
* 11Sep2002 janetinc@us.ibm.com
- * added readv/writev support.
+ * added readv/writev support.
* 29Oct2002 Andrew Morton
* rewrote bio_add_page() support.
* 30Oct2002 pbadari@us.ibm.com
@@ -39,183 +39,37 @@
#include <linux/prefetch.h>
#include <linux/aio.h>

-/*
- * How many user pages to map in one call to get_user_pages(). This determines
- * the size of a structure in the slab cache
- */
-#define DIO_PAGES 64
-
-/*
- * This code generally works in units of "dio_blocks". A dio_block is
- * somewhere between the hard sector size and the filesystem block size. it
- * is determined on a per-invocation basis. When talking to the filesystem
- * we need to convert dio_blocks to fs_blocks by scaling the dio_block quantity
- * down by dio->blkfactor. Similarly, fs-blocksize quantities are converted
- * to bio_block quantities by shifting left by blkfactor.
- *
- * If blkfactor is zero then the user's request was aligned to the filesystem's
- * blocksize.
- */
-
/* dio_state only used in the submission path */
-
struct dio_submit {
- struct bio *bio; /* bio under assembly */
- unsigned blkbits; /* doesn't change */
- unsigned blkfactor; /* When we're using an alignment which
- is finer than the filesystem's soft
- blocksize, this specifies how much
- finer. blkfactor=2 means 1/4-block
- alignment. Does not change */
- unsigned start_zero_done; /* flag: sub-blocksize zeroing has
- been performed at the start of a
- write */
- int pages_in_io; /* approximate total IO pages */
- size_t size; /* total request size (doesn't change)*/
- sector_t block_in_file; /* Current offset into the underlying
- file in dio_block units. */
- unsigned blocks_available; /* At block_in_file. changes */
- int reap_counter; /* rate limit reaping */
- sector_t final_block_in_request;/* doesn't change */
- unsigned first_block_in_page; /* doesn't change, Used only once */
- int boundary; /* prev block is at a boundary */
- get_block_t *get_block; /* block mapping function */
- dio_submit_t *submit_io; /* IO submition function */
-
- loff_t logical_offset_in_bio; /* current first logical block in bio */
- sector_t final_block_in_bio; /* current final block in bio + 1 */
- sector_t next_block_for_io; /* next block to be put under IO,
- in dio_blocks units */
-
- /*
- * Deferred addition of a page to the dio. These variables are
- * private to dio_send_cur_page(), submit_page_section() and
- * dio_bio_add_page().
- */
- struct page *cur_page; /* The page */
- unsigned cur_page_offset; /* Offset into it, in bytes */
- unsigned cur_page_len; /* Nr of bytes at cur_page_offset */
- sector_t cur_page_block; /* Where it starts */
- loff_t cur_page_fs_offset; /* Offset in file */
-
- /*
- * Page fetching state. These variables belong to dio_refill_pages().
- */
- int curr_page; /* changes */
- int total_pages; /* doesn't change */
- unsigned long curr_user_address;/* changes */
-
- /*
- * Page queue. These variables belong to dio_refill_pages() and
- * dio_get_page().
- */
- unsigned head; /* next page to process */
- unsigned tail; /* last valid page + 1 */
+ get_block_t *get_block; /* block mapping function */
+ dio_submit_t *submit_io; /* IO submition function */
+ unsigned i_blkbits;
};

/* dio_state communicated between submission path and end_io */
struct dio {
- int flags; /* doesn't change */
- int rw;
- struct inode *inode;
- loff_t i_size; /* i_size when submitted */
- dio_iodone_t *end_io; /* IO completion function */
+ int flags; /* doesn't change */
+ int rw;
+ struct inode *inode;
+ loff_t i_size; /* i_size when submitted */

- void *private; /* copy from map_bh.b_private */
+ dio_iodone_t *end_io; /* IO completion function */
+ void *private; /* copy from map_bh.b_private */

/* BIO completion state */
- spinlock_t bio_lock; /* protects BIO fields below */
- int page_errors; /* errno from get_user_pages() */
- int is_async; /* is IO async ? */
- int io_error; /* IO error in completion path */
- unsigned long refcount; /* direct_io_worker() and bios */
- struct bio *bio_list; /* singly linked via bi_private */
+ int page_error; /* errno from get_user_pages() */
+ int io_error; /* IO error in completion path */
+ atomic_long_t refcount; /* direct_io_worker() and bios */
struct task_struct *waiter; /* waiting task (NULL if none) */

/* AIO related stuff */
- struct kiocb *iocb; /* kiocb */
- ssize_t result; /* IO result */
-
- /*
- * pages[] (and any fields placed after it) are not zeroed out at
- * allocation time. Don't add new fields after pages[] unless you
- * wish that they not be zeroed.
- */
- struct page *pages[DIO_PAGES]; /* page buffer */
-} ____cacheline_aligned_in_smp;
+ struct kiocb *iocb; /* kiocb */
+ ssize_t result; /* IO result */

-static struct kmem_cache *dio_cache __read_mostly;
-
-/*
- * How many pages are in the queue?
- */
-static inline unsigned dio_pages_present(struct dio_submit *sdio)
-{
- return sdio->tail - sdio->head;
-}
-
-/*
- * Go grab and pin some userspace pages. Typically we'll get 64 at a time.
- */
-static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)
-{
- int ret;
- int nr_pages;
-
- nr_pages = min(sdio->total_pages - sdio->curr_page, DIO_PAGES);
- ret = get_user_pages_fast(
- sdio->curr_user_address, /* Where from? */
- nr_pages, /* How many pages? */
- dio->rw == READ, /* Write to memory? */
- &dio->pages[0]); /* Put results here */
-
- if (ret < 0 && sdio->blocks_available && (dio->rw & WRITE)) {
- struct page *page = ZERO_PAGE(0);
- /*
- * A memory fault, but the filesystem has some outstanding
- * mapped blocks. We need to use those blocks up to avoid
- * leaking stale data in the file.
- */
- if (dio->page_errors == 0)
- dio->page_errors = ret;
- page_cache_get(page);
- dio->pages[0] = page;
- sdio->head = 0;
- sdio->tail = 1;
- ret = 0;
- goto out;
- }
-
- if (ret >= 0) {
- sdio->curr_user_address += ret * PAGE_SIZE;
- sdio->curr_page += ret;
- sdio->head = 0;
- sdio->tail = ret;
- ret = 0;
- }
-out:
- return ret;
-}
-
-/*
- * Get another userspace page. Returns an ERR_PTR on error. Pages are
- * buffered inside the dio so that we can call get_user_pages() against a
- * decent number of pages, less frequently. To provide nicer use of the
- * L1 cache.
- */
-static inline struct page *dio_get_page(struct dio *dio,
- struct dio_submit *sdio)
-{
- if (dio_pages_present(sdio) == 0) {
- int ret;
+ struct bio bio;
+};

- ret = dio_refill_pages(dio, sdio);
- if (ret)
- return ERR_PTR(ret);
- BUG_ON(dio_pages_present(sdio) == 0);
- }
- return dio->pages[sdio->head++];
-}
+static struct bio_set *dio_pool __read_mostly;

/**
* dio_complete() - called when all DIO BIO I/O has been completed
@@ -234,25 +88,18 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is
{
ssize_t transferred = 0;

- /*
- * AIO submission can race with bio completion to get here while
- * expecting to have the last io completed by bio completion.
- * In that case -EIOCBQUEUED is in fact not an error we want
- * to preserve through this call.
- */
- if (ret == -EIOCBQUEUED)
- ret = 0;
-
if (dio->result) {
transferred = dio->result;

+ /* XXX: dio_send_bio() could do this */
+
/* Check for short read case */
if ((dio->rw == READ) && ((offset + transferred) > dio->i_size))
transferred = dio->i_size - offset;
}

if (ret == 0)
- ret = dio->page_errors;
+ ret = dio->page_error;
if (ret == 0)
ret = dio->io_error;
if (ret == 0)
@@ -267,53 +114,11 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is
aio_complete(dio->iocb, ret, 0);
}

+ bio_put(&dio->bio);
return ret;
}

-static int dio_bio_complete(struct dio *dio, struct bio *bio);
-/*
- * Asynchronous IO callback.
- */
-static void dio_bio_end_aio(struct bio *bio, int error)
-{
- struct dio *dio = bio->bi_private;
- unsigned long remaining;
- unsigned long flags;
-
- /* cleanup the bio */
- dio_bio_complete(dio, bio);
-
- spin_lock_irqsave(&dio->bio_lock, flags);
- remaining = --dio->refcount;
- if (remaining == 1 && dio->waiter)
- wake_up_process(dio->waiter);
- spin_unlock_irqrestore(&dio->bio_lock, flags);
-
- if (remaining == 0) {
- dio_complete(dio, dio->iocb->ki_pos, 0, true);
- kmem_cache_free(dio_cache, dio);
- }
-}
-
-/*
- * The BIO completion handler simply queues the BIO up for the process-context
- * handler.
- *
- * During I/O bi_private points at the dio. After I/O, bi_private is used to
- * implement a singly-linked list of completed BIOs, at dio->bio_list.
- */
-static void dio_bio_end_io(struct bio *bio, int error)
-{
- struct dio *dio = bio->bi_private;
- unsigned long flags;
-
- spin_lock_irqsave(&dio->bio_lock, flags);
- bio->bi_private = dio->bio_list;
- dio->bio_list = bio;
- if (--dio->refcount == 1 && dio->waiter)
- wake_up_process(dio->waiter);
- spin_unlock_irqrestore(&dio->bio_lock, flags);
-}
+#define DIO_WAKEUP (1U << 31)

/**
* dio_end_io - handle the end io action for the given bio
@@ -327,693 +132,321 @@ static void dio_bio_end_io(struct bio *bio, int error)
void dio_end_io(struct bio *bio, int error)
{
struct dio *dio = bio->bi_private;
+ unsigned long remaining;

- if (dio->is_async)
- dio_bio_end_aio(bio, error);
- else
- dio_bio_end_io(bio, error);
+ if (error)
+ dio->io_error = -EIO;
+
+ if (dio->rw == READ) {
+ bio_check_pages_dirty(bio); /* transfers ownership */
+ } else {
+ struct bio_vec *bv;
+ int i;
+
+ bio_for_each_segment_all(bv, bio, i)
+ page_cache_release(bv->bv_page);
+ bio_put(bio);
+ }
+
+ remaining = atomic_long_dec_return(&dio->refcount);
+
+ if (remaining == DIO_WAKEUP)
+ wake_up_process(dio->waiter);
+ else if (!remaining)
+ dio_complete(dio, dio->iocb->ki_pos, 0, true);
}
EXPORT_SYMBOL_GPL(dio_end_io);

-static inline void
-dio_bio_alloc(struct dio *dio, struct dio_submit *sdio,
- struct block_device *bdev,
- sector_t first_sector, int nr_vecs)
+static void dio_wait_completion(struct dio *dio)
{
- struct bio *bio;
-
- /*
- * bio_alloc() is guaranteed to return a bio when called with
- * __GFP_WAIT and we request a valid number of vectors.
- */
- bio = bio_alloc(GFP_KERNEL, nr_vecs);
+ if (atomic_long_add_return(DIO_WAKEUP - 1,
+ &dio->refcount) == DIO_WAKEUP)
+ return;

- bio->bi_bdev = bdev;
- bio->bi_iter.bi_sector = first_sector;
- if (dio->is_async)
- bio->bi_end_io = dio_bio_end_aio;
- else
- bio->bi_end_io = dio_bio_end_io;
+ while (1) {
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ if (atomic_long_read(&dio->refcount) == DIO_WAKEUP)
+ break;

- sdio->bio = bio;
- sdio->logical_offset_in_bio = sdio->cur_page_fs_offset;
+ io_schedule();
+ }
+ __set_current_state(TASK_RUNNING);
}

/*
- * In the AIO read case we speculatively dirty the pages before starting IO.
- * During IO completion, any of these pages which happen to have been written
- * back will be redirtied by bio_check_pages_dirty().
+ * For reads we speculatively dirty the pages before starting IO. During IO
+ * completion, any of these pages which happen to have been written back will be
+ * redirtied by bio_check_pages_dirty().
*
* bios hold a dio reference between submit_bio and ->end_io.
*/
-static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)
+static void dio_bio_submit(struct dio *dio, struct dio_submit *sdio,
+ struct bio *bio, loff_t offset)
{
- struct bio *bio = sdio->bio;
- unsigned long flags;
-
- bio->bi_private = dio;
-
- spin_lock_irqsave(&dio->bio_lock, flags);
- dio->refcount++;
- spin_unlock_irqrestore(&dio->bio_lock, flags);
-
- if (dio->is_async && dio->rw == READ)
- bio_set_pages_dirty(bio);
+ /*
+ * Read accounting is performed in submit_bio()
+ */
+ if (dio->rw & WRITE)
+ task_io_account_write(bio->bi_iter.bi_size);

if (sdio->submit_io)
sdio->submit_io(dio->rw, bio, dio->inode,
- sdio->logical_offset_in_bio);
+ offset >> sdio->i_blkbits);
else
submit_bio(dio->rw, bio);
-
- sdio->bio = NULL;
- sdio->boundary = 0;
- sdio->logical_offset_in_bio = 0;
-}
-
-/*
- * Release any resources in case of a failure
- */
-static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio)
-{
- while (dio_pages_present(sdio))
- page_cache_release(dio_get_page(dio, sdio));
-}
-
-/*
- * Wait for the next BIO to complete. Remove it and return it. NULL is
- * returned once all BIOs have been completed. This must only be called once
- * all bios have been issued so that dio->refcount can only decrease. This
- * requires that that the caller hold a reference on the dio.
- */
-static struct bio *dio_await_one(struct dio *dio)
-{
- unsigned long flags;
- struct bio *bio = NULL;
-
- spin_lock_irqsave(&dio->bio_lock, flags);
-
- /*
- * Wait as long as the list is empty and there are bios in flight. bio
- * completion drops the count, maybe adds to the list, and wakes while
- * holding the bio_lock so we don't need set_current_state()'s barrier
- * and can call it after testing our condition.
- */
- while (dio->refcount > 1 && dio->bio_list == NULL) {
- __set_current_state(TASK_UNINTERRUPTIBLE);
- dio->waiter = current;
- spin_unlock_irqrestore(&dio->bio_lock, flags);
- io_schedule();
- /* wake up sets us TASK_RUNNING */
- spin_lock_irqsave(&dio->bio_lock, flags);
- dio->waiter = NULL;
- }
- if (dio->bio_list) {
- bio = dio->bio_list;
- dio->bio_list = bio->bi_private;
- }
- spin_unlock_irqrestore(&dio->bio_lock, flags);
- return bio;
}

/*
- * Process one completed BIO. No locks are held.
+ * Clean any dirty buffers in the blockdev mapping which alias newly-created
+ * file blocks. Only called for S_ISREG files - blockdevs do not set buffer_new
*/
-static int dio_bio_complete(struct dio *dio, struct bio *bio)
+static void clean_blockdev_aliases(struct dio *dio, struct dio_submit *sdio,
+ struct buffer_head *map_bh)
{
- const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
- struct bio_vec *bvec;
unsigned i;
+ unsigned nblocks;

- if (!uptodate)
- dio->io_error = -EIO;
+ nblocks = map_bh->b_size >> sdio->i_blkbits;

- if (dio->is_async && dio->rw == READ) {
- bio_check_pages_dirty(bio); /* transfers ownership */
- } else {
- bio_for_each_segment_all(bvec, bio, i) {
- struct page *page = bvec->bv_page;
-
- if (dio->rw == READ && !PageCompound(page))
- set_page_dirty_lock(page);
- page_cache_release(page);
- }
- bio_put(bio);
- }
- return uptodate ? 0 : -EIO;
+ for (i = 0; i < nblocks; i++)
+ unmap_underlying_metadata(map_bh->b_bdev,
+ map_bh->b_blocknr + i);
}

-/*
- * Wait on and process all in-flight BIOs. This must only be called once
- * all bios have been issued so that the refcount can only decrease.
- * This just waits for all bios to make it through dio_bio_complete. IO
- * errors are propagated through dio->io_error and should be propagated via
- * dio_complete().
- */
-static void dio_await_completion(struct dio *dio)
-{
- struct bio *bio;
- do {
- bio = dio_await_one(dio);
- if (bio)
- dio_bio_complete(dio, bio);
- } while (bio);
-}
+struct dio_mapping {
+ enum {
+ MAP_MAPPED,
+ MAP_NEW,
+ MAP_UNMAPPED,
+ } state;

-/*
- * A really large O_DIRECT read or write can generate a lot of BIOs. So
- * to keep the memory consumption sane we periodically reap any completed BIOs
- * during the BIO generation phase.
- *
- * This also helps to limit the peak amount of pinned userspace memory.
- */
-static inline int dio_bio_reap(struct dio *dio, struct dio_submit *sdio)
-{
- int ret = 0;
-
- if (sdio->reap_counter++ >= 64) {
- while (dio->bio_list) {
- unsigned long flags;
- struct bio *bio;
- int ret2;
-
- spin_lock_irqsave(&dio->bio_lock, flags);
- bio = dio->bio_list;
- dio->bio_list = bio->bi_private;
- spin_unlock_irqrestore(&dio->bio_lock, flags);
- ret2 = dio_bio_complete(dio, bio);
- if (ret == 0)
- ret = ret2;
- }
- sdio->reap_counter = 0;
- }
- return ret;
-}
+ struct block_device *bdev;
+ sector_t sector;
+ size_t size;
+};

-/*
- * Call into the fs to map some more disk blocks. We record the current number
- * of available blocks at sdio->blocks_available. These are in units of the
- * fs blocksize, (1 << inode->i_blkbits).
- *
- * The fs is allowed to map lots of blocks at once. If it wants to do that,
- * it uses the passed inode-relative block number as the file offset, as usual.
- *
- * get_block() is passed the number of i_blkbits-sized blocks which direct_io
- * has remaining to do. The fs should not map more than this number of blocks.
- *
- * If the fs has mapped a lot of blocks, it should populate bh->b_size to
- * indicate how much contiguous disk space has been made available at
- * bh->b_blocknr.
- *
- * If *any* of the mapped blocks are new, then the fs must set buffer_new().
- * This isn't very efficient...
- *
- * In the case of filesystem holes: the fs may return an arbitrarily-large
- * hole by returning an appropriate value in b_size and by clearing
- * buffer_mapped(). However the direct-io code will only process holes one
- * block at a time - it will repeatedly call get_block() as it walks the hole.
- */
-static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
- struct buffer_head *map_bh)
+static int get_blocks(struct dio *dio, struct dio_submit *sdio,
+ loff_t offset, size_t size,
+ struct dio_mapping *map)
{
- int ret;
- sector_t fs_startblk; /* Into file, in filesystem-sized blocks */
- sector_t fs_endblk; /* Into file, in filesystem-sized blocks */
- unsigned long fs_count; /* Number of filesystem-sized blocks */
- int create;
- unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor;
+ struct buffer_head map_bh = { 0, };
+ int ret, create;
+ unsigned i_mask = (1 << sdio->i_blkbits) - 1;
+ unsigned fs_offset = offset & i_mask;
+ sector_t fs_block = offset >> sdio->i_blkbits;

/*
- * If there was a memory error and we've overwritten all the
- * mapped blocks then we can now return that memory error
+ * For writes inside i_size on a DIO_SKIP_HOLES filesystem we
+ * forbid block creations: only overwrites are permitted.
+ * We will return early to the caller once we see an
+ * unmapped buffer head returned, and the caller will fall
+ * back to buffered I/O.
+ *
+ * Otherwise the decision is left to the get_blocks method,
+ * which may decide to handle it or also return an unmapped
+ * buffer head.
*/
- ret = dio->page_errors;
- if (ret == 0) {
- BUG_ON(sdio->block_in_file >= sdio->final_block_in_request);
- fs_startblk = sdio->block_in_file >> sdio->blkfactor;
- fs_endblk = (sdio->final_block_in_request - 1) >>
- sdio->blkfactor;
- fs_count = fs_endblk - fs_startblk + 1;
-
- map_bh->b_state = 0;
- map_bh->b_size = fs_count << i_blkbits;
-
- /*
- * For writes inside i_size on a DIO_SKIP_HOLES filesystem we
- * forbid block creations: only overwrites are permitted.
- * We will return early to the caller once we see an
- * unmapped buffer head returned, and the caller will fall
- * back to buffered I/O.
- *
- * Otherwise the decision is left to the get_blocks method,
- * which may decide to handle it or also return an unmapped
- * buffer head.
- */
- create = dio->rw & WRITE;
- if (dio->flags & DIO_SKIP_HOLES) {
- if (sdio->block_in_file < (i_size_read(dio->inode) >>
- sdio->blkbits))
- create = 0;
- }
-
- ret = (*sdio->get_block)(dio->inode, fs_startblk,
- map_bh, create);
-
- /* Store for completion */
- dio->private = map_bh->b_private;
+ create = dio->rw & WRITE;
+ if (dio->flags & DIO_SKIP_HOLES) {
+ if (fs_block < dio->i_size >> sdio->i_blkbits)
+ create = 0;
}
- return ret;
-}

-/*
- * There is no bio. Make one now.
- */
-static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio,
- sector_t start_sector, struct buffer_head *map_bh)
-{
- sector_t sector;
- int ret, nr_pages;
+ map_bh.b_state = 0;
+ map_bh.b_size = size + fs_offset;

- ret = dio_bio_reap(dio, sdio);
+ ret = sdio->get_block(dio->inode, fs_block,
+ &map_bh, create);
if (ret)
- goto out;
- sector = start_sector << (sdio->blkbits - 9);
- nr_pages = min(sdio->pages_in_io, bio_get_nr_vecs(map_bh->b_bdev));
- nr_pages = min(nr_pages, BIO_MAX_PAGES);
- BUG_ON(nr_pages <= 0);
- dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages);
- sdio->boundary = 0;
-out:
- return ret;
-}
+ return ret;

-/*
- * Attempt to put the current chunk of 'cur_page' into the current BIO. If
- * that was successful then update final_block_in_bio and take a ref against
- * the just-added page.
- *
- * Return zero on success. Non-zero means the caller needs to start a new BIO.
- */
-static inline int dio_bio_add_page(struct dio_submit *sdio)
-{
- int ret;
+ /* Store for completion */
+ dio->private = map_bh.b_private;

- ret = bio_add_page(sdio->bio, sdio->cur_page,
- sdio->cur_page_len, sdio->cur_page_offset);
- if (ret == sdio->cur_page_len) {
- /*
- * Decrement count only, if we are done with this page
- */
- if ((sdio->cur_page_len + sdio->cur_page_offset) == PAGE_SIZE)
- sdio->pages_in_io--;
- page_cache_get(sdio->cur_page);
- sdio->final_block_in_bio = sdio->cur_page_block +
- (sdio->cur_page_len >> sdio->blkbits);
- ret = 0;
- } else {
- ret = 1;
- }
- return ret;
-}
-
-/*
- * Put cur_page under IO. The section of cur_page which is described by
- * cur_page_offset,cur_page_len is put into a BIO. The section of cur_page
- * starts on-disk at cur_page_block.
- *
- * We take a ref against the page here (on behalf of its presence in the bio).
- *
- * The caller of this function is responsible for removing cur_page from the
- * dio, and for dropping the refcount which came from that presence.
- */
-static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,
- struct buffer_head *map_bh)
-{
- int ret = 0;
+ if (!buffer_mapped(&map_bh))
+ map->state = MAP_UNMAPPED;
+ else if (buffer_new(&map_bh))
+ map->state = MAP_NEW;
+ else
+ map->state = MAP_MAPPED;

- if (sdio->bio) {
- loff_t cur_offset = sdio->cur_page_fs_offset;
- loff_t bio_next_offset = sdio->logical_offset_in_bio +
- sdio->bio->bi_iter.bi_size;
+ /* Holes always 1 block? */
+ if (map->state == MAP_UNMAPPED)
+ map_bh.b_size = 1 << sdio->i_blkbits;

- /*
- * See whether this new request is contiguous with the old.
- *
- * Btrfs cannot handle having logically non-contiguous requests
- * submitted. For example if you have
- *
- * Logical: [0-4095][HOLE][8192-12287]
- * Physical: [0-4095] [4096-8191]
- *
- * We cannot submit those pages together as one BIO. So if our
- * current logical offset in the file does not equal what would
- * be the next logical offset in the bio, submit the bio we
- * have.
- */
- if (sdio->final_block_in_bio != sdio->cur_page_block ||
- cur_offset != bio_next_offset)
- dio_bio_submit(dio, sdio);
- }
+ if (map->state == MAP_NEW)
+ clean_blockdev_aliases(dio, sdio, &map_bh);

- if (sdio->bio == NULL) {
- ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh);
- if (ret)
- goto out;
- }
+ BUG_ON(map_bh.b_size <= fs_offset);
+
+ map->bdev = map_bh.b_bdev;
+ map->sector = (map_bh.b_blocknr << (sdio->i_blkbits - 9)) +
+ (fs_offset >> 9);
+ map->size = min(map_bh.b_size - fs_offset, size);

- if (dio_bio_add_page(sdio) != 0) {
- dio_bio_submit(dio, sdio);
- ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh);
- if (ret == 0) {
- ret = dio_bio_add_page(sdio);
- BUG_ON(ret != 0);
- }
- }
-out:
return ret;
}

-/*
- * An autonomous function to put a chunk of a page under deferred IO.
- *
- * The caller doesn't actually know (or care) whether this piece of page is in
- * a BIO, or is under IO or whatever. We just take care of all possible
- * situations here. The separation between the logic of do_direct_IO() and
- * that of submit_page_section() is important for clarity. Please don't break.
- *
- * The chunk of page starts on-disk at blocknr.
- *
- * We perform deferred IO, by recording the last-submitted page inside our
- * private part of the dio structure. If possible, we just expand the IO
- * across that page here.
- *
- * If that doesn't work out then we put the old page into the bio and add this
- * page to the dio instead.
- */
-static inline int
-submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page,
- unsigned offset, unsigned len, sector_t blocknr,
- struct buffer_head *map_bh)
+static void dio_write_zeroes(struct dio *dio, struct bio *parent,
+ sector_t sector, size_t size)
{
- int ret = 0;
+ unsigned pages = DIV_ROUND_UP(size, PAGE_SIZE);
+ struct bio *bio = bio_alloc(GFP_KERNEL, pages);

- if (dio->rw & WRITE) {
- /*
- * Read accounting is performed in submit_bio()
- */
- task_io_account_write(len);
+ while (pages--) {
+ bio->bi_io_vec[pages].bv_page = ZERO_PAGE(0);
+ bio->bi_io_vec[pages].bv_len = PAGE_SIZE;
+ bio->bi_io_vec[pages].bv_offset = 0;
}

- /*
- * Can we just grow the current page's presence in the dio?
- */
- if (sdio->cur_page == page &&
- sdio->cur_page_offset + sdio->cur_page_len == offset &&
- sdio->cur_page_block +
- (sdio->cur_page_len >> sdio->blkbits) == blocknr) {
- sdio->cur_page_len += len;
- goto out;
- }
-
- /*
- * If there's a deferred page already there then send it.
- */
- if (sdio->cur_page) {
- ret = dio_send_cur_page(dio, sdio, map_bh);
- page_cache_release(sdio->cur_page);
- sdio->cur_page = NULL;
- if (ret)
- return ret;
- }
+ bio->bi_bdev = parent->bi_bdev;
+ bio->bi_iter.bi_sector = sector;
+ bio->bi_iter.bi_size = size;

- page_cache_get(page); /* It is in dio */
- sdio->cur_page = page;
- sdio->cur_page_offset = offset;
- sdio->cur_page_len = len;
- sdio->cur_page_block = blocknr;
- sdio->cur_page_fs_offset = sdio->block_in_file << sdio->blkbits;
-out:
- /*
- * If sdio->boundary then we want to schedule the IO now to
- * avoid metadata seeks.
- */
- if (sdio->boundary) {
- ret = dio_send_cur_page(dio, sdio, map_bh);
- dio_bio_submit(dio, sdio);
- page_cache_release(sdio->cur_page);
- sdio->cur_page = NULL;
- }
- return ret;
+ bio_chain(bio, parent);
+ submit_bio(WRITE, bio);
}

-/*
- * Clean any dirty buffers in the blockdev mapping which alias newly-created
- * file blocks. Only called for S_ISREG files - blockdevs do not set
- * buffer_new
- */
-static void clean_blockdev_aliases(struct dio *dio, struct buffer_head *map_bh)
+static void dio_zero_partial_block(struct dio *dio, struct dio_submit *sdio,
+ struct bio *bio, loff_t offset,
+ struct dio_mapping *map)
{
- unsigned i;
- unsigned nblocks;
-
- nblocks = map_bh->b_size >> dio->inode->i_blkbits;
-
- for (i = 0; i < nblocks; i++) {
- unmap_underlying_metadata(map_bh->b_bdev,
- map_bh->b_blocknr + i);
+ if ((dio->rw & WRITE) && map->state == MAP_NEW) {
+ unsigned blksize = 1 << sdio->i_blkbits;
+ unsigned blkmask = blksize - 1;
+ unsigned front = offset & blkmask;
+ unsigned back = (offset + bio->bi_iter.bi_size) & blkmask;
+
+ if (front)
+ dio_write_zeroes(dio, bio,
+ bio->bi_iter.bi_sector - (front >> 9),
+ front);
+
+ if (back)
+ dio_write_zeroes(dio, bio, bio_end_sector(bio),
+ blksize - back);
}
}

-/*
- * If we are not writing the entire block and get_block() allocated
- * the block for us, we need to fill-in the unused portion of the
- * block with zeros. This happens only if user-buffer, fileoffset or
- * io length is not filesystem block-size multiple.
- *
- * `end' is zero if we're doing the start of the IO, 1 at the end of the
- * IO.
- */
-static inline void dio_zero_block(struct dio *dio, struct dio_submit *sdio,
- int end, struct buffer_head *map_bh)
+static int dio_send_bio(struct dio *dio, struct dio_submit *sdio,
+ struct bio *bio, loff_t offset)
{
- unsigned dio_blocks_per_fs_block;
- unsigned this_chunk_blocks; /* In dio_blocks */
- unsigned this_chunk_bytes;
- struct page *page;
+ struct dio_mapping map;
+ struct bio *split;
+ int ret;

- sdio->start_zero_done = 1;
- if (!sdio->blkfactor || !buffer_new(map_bh))
- return;
+ while (1) {
+ if (dio->rw == READ && offset >= dio->i_size)
+ break;

- dio_blocks_per_fs_block = 1 << sdio->blkfactor;
- this_chunk_blocks = sdio->block_in_file & (dio_blocks_per_fs_block - 1);
+ ret = get_blocks(dio, sdio, offset, bio->bi_iter.bi_size, &map);
+ if (ret)
+ break;

- if (!this_chunk_blocks)
- return;
+ if (map.state != MAP_UNMAPPED) {
+ split = bio_next_split(bio, map.size >> 9,
+ GFP_KERNEL, fs_bio_set);

- /*
- * We need to zero out part of an fs block. It is either at the
- * beginning or the end of the fs block.
- */
- if (end)
- this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks;
+ if (split != bio)
+ bio_chain(split, bio);

- this_chunk_bytes = this_chunk_blocks << sdio->blkbits;
+ split->bi_bdev = map.bdev;
+ split->bi_iter.bi_sector = map.sector;

- page = ZERO_PAGE(0);
- if (submit_page_section(dio, sdio, page, 0, this_chunk_bytes,
- sdio->next_block_for_io, map_bh))
- return;
+ dio_zero_partial_block(dio, sdio, split, offset, &map);

- sdio->next_block_for_io += this_chunk_blocks;
-}
+ dio->result += map.size;
+ dio_bio_submit(dio, sdio, split, offset);

-/*
- * Walk the user pages, and the file, mapping blocks to disk and generating
- * a sequence of (page,offset,len,block) mappings. These mappings are injected
- * into submit_page_section(), which takes care of the next stage of submission
- *
- * Direct IO against a blockdev is different from a file. Because we can
- * happily perform page-sized but 512-byte aligned IOs. It is important that
- * blockdev IO be able to have fine alignment and large sizes.
- *
- * So what we do is to permit the ->get_block function to populate bh.b_size
- * with the size of IO which is permitted at this offset and this i_blkbits.
- *
- * For best results, the blockdev should be set up with 512-byte i_blkbits and
- * it should set b_size to PAGE_SIZE or more inside get_block(). This gives
- * fine alignment but still allows this function to work in PAGE_SIZE units.
- */
-static int do_direct_IO(struct dio *dio, struct dio_submit *sdio,
- struct buffer_head *map_bh)
-{
- const unsigned blkbits = sdio->blkbits;
- const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
- struct page *page;
- unsigned block_in_page;
- int ret = 0;
-
- /* The I/O can start at any block offset within the first page */
- block_in_page = sdio->first_block_in_page;
-
- while (sdio->block_in_file < sdio->final_block_in_request) {
- page = dio_get_page(dio, sdio);
- if (IS_ERR(page)) {
- ret = PTR_ERR(page);
- goto out;
- }
+ if (split == bio)
+ return 0;
+ } else {
+ /* Hole */

- while (block_in_page < blocks_per_page) {
- unsigned offset_in_page = block_in_page << blkbits;
- unsigned this_chunk_bytes; /* # of bytes mapped */
- unsigned this_chunk_blocks; /* # of blocks */
- unsigned u;
-
- if (sdio->blocks_available == 0) {
- /*
- * Need to go and map some more disk
- */
- unsigned long blkmask;
- unsigned long dio_remainder;
-
- ret = get_more_blocks(dio, sdio, map_bh);
- if (ret) {
- page_cache_release(page);
- goto out;
- }
- if (!buffer_mapped(map_bh))
- goto do_holes;
-
- sdio->blocks_available =
- map_bh->b_size >> sdio->blkbits;
- sdio->next_block_for_io =
- map_bh->b_blocknr << sdio->blkfactor;
- if (buffer_new(map_bh))
- clean_blockdev_aliases(dio, map_bh);
-
- if (!sdio->blkfactor)
- goto do_holes;
-
- blkmask = (1 << sdio->blkfactor) - 1;
- dio_remainder = (sdio->block_in_file & blkmask);
-
- /*
- * If we are at the start of IO and that IO
- * starts partway into a fs-block,
- * dio_remainder will be non-zero. If the IO
- * is a read then we can simply advance the IO
- * cursor to the first block which is to be
- * read. But if the IO is a write and the
- * block was newly allocated we cannot do that;
- * the start of the fs block must be zeroed out
- * on-disk
- */
- if (!buffer_new(map_bh))
- sdio->next_block_for_io += dio_remainder;
- sdio->blocks_available -= dio_remainder;
- }
-do_holes:
- /* Handle holes */
- if (!buffer_mapped(map_bh)) {
- loff_t i_size_aligned;
-
- /* AKPM: eargh, -ENOTBLK is a hack */
- if (dio->rw & WRITE) {
- page_cache_release(page);
- return -ENOTBLK;
- }
-
- /*
- * Be sure to account for a partial block as the
- * last block in the file
- */
- i_size_aligned = ALIGN(i_size_read(dio->inode),
- 1 << blkbits);
- if (sdio->block_in_file >=
- i_size_aligned >> blkbits) {
- /* We hit eof */
- page_cache_release(page);
- goto out;
- }
- zero_user(page, block_in_page << blkbits,
- 1 << blkbits);
- sdio->block_in_file++;
- block_in_page++;
- goto next_block;
+ /* AKPM: eargh, -ENOTBLK is a hack */
+ if (dio->rw & WRITE) {
+ ret = -ENOTBLK;
+ break;
}

- /*
- * If we're performing IO which has an alignment which
- * is finer than the underlying fs, go check to see if
- * we must zero out the start of this block.
- */
- if (unlikely(sdio->blkfactor && !sdio->start_zero_done))
- dio_zero_block(dio, sdio, 0, map_bh);
-
- /*
- * Work out, in this_chunk_blocks, how much disk we
- * can add to this page
- */
- this_chunk_blocks = sdio->blocks_available;
- u = (PAGE_SIZE - offset_in_page) >> blkbits;
- if (this_chunk_blocks > u)
- this_chunk_blocks = u;
- u = sdio->final_block_in_request - sdio->block_in_file;
- if (this_chunk_blocks > u)
- this_chunk_blocks = u;
- this_chunk_bytes = this_chunk_blocks << blkbits;
- BUG_ON(this_chunk_bytes == 0);
-
- if (this_chunk_blocks == sdio->blocks_available)
- sdio->boundary = buffer_boundary(map_bh);
- ret = submit_page_section(dio, sdio, page,
- offset_in_page,
- this_chunk_bytes,
- sdio->next_block_for_io,
- map_bh);
- if (ret) {
- page_cache_release(page);
- goto out;
- }
- sdio->next_block_for_io += this_chunk_blocks;
-
- sdio->block_in_file += this_chunk_blocks;
- block_in_page += this_chunk_blocks;
- sdio->blocks_available -= this_chunk_blocks;
-next_block:
- BUG_ON(sdio->block_in_file > sdio->final_block_in_request);
- if (sdio->block_in_file == sdio->final_block_in_request)
+ swap(bio->bi_iter.bi_size, map.size);
+ zero_fill_bio(bio);
+ swap(bio->bi_iter.bi_size, map.size);
+
+ dio->result += map.size;
+ bio_advance(bio, map.size);
+
+ if (!bio->bi_iter.bi_size)
break;
}

- /* Drop the ref which was taken in get_user_pages() */
- page_cache_release(page);
- block_in_page = 0;
+ offset += map.size;
}
-out:
+
+ bio_endio(bio, 0);
return ret;
}

-static inline int drop_refcount(struct dio *dio)
+static int dio_alloc_bios(struct dio *dio, struct dio_submit *sdio,
+ const struct iovec *iov, loff_t offset,
+ unsigned long nr_segs, unsigned nr_pages)
{
- int ret2;
- unsigned long flags;
+ ssize_t ret;
+ size_t seg_done = 0;
+ unsigned seg = 0;
+ struct bio *bio;

- /*
- * Sync will always be dropping the final ref and completing the
- * operation. AIO can if it was a broken operation described above or
- * in fact if all the bios race to complete before we get here. In
- * that case dio_complete() translates the EIOCBQUEUED into the proper
- * return code that the caller will hand to aio_complete().
- *
- * This is managed by the bio_lock instead of being an atomic_t so that
- * completion paths can drop their ref and use the remaining count to
- * decide to wake the submission path atomically.
- */
- spin_lock_irqsave(&dio->bio_lock, flags);
- ret2 = --dio->refcount;
- spin_unlock_irqrestore(&dio->bio_lock, flags);
- return ret2;
+ bio = &dio->bio;
+ bio_get(bio);
+ goto start;
+
+ while (seg < nr_segs) {
+ BUG_ON(!nr_pages);
+
+ bio = bio_alloc(GFP_KERNEL,
+ min_t(unsigned, BIO_MAX_PAGES, nr_pages));
+start:
+ bio->bi_private = dio;
+ bio->bi_end_io = dio_end_io;
+
+ while (bio->bi_vcnt < bio->bi_max_vecs &&
+ seg < nr_segs) {
+ ret = bio_get_user_pages(bio,
+ (size_t) iov[seg].iov_base + seg_done,
+ iov[seg].iov_len - seg_done,
+ dio->rw == READ);
+ if (ret < 0) {
+ struct bio_vec *bv;
+ int i;
+
+ bio_for_each_segment_all(bv, bio, i)
+ page_cache_release(bv->bv_page);
+ bio_put(bio);
+
+ dio->page_error = ret;
+ return 0;
+ }
+
+ seg_done += ret;
+
+ if (seg_done == iov[seg].iov_len) {
+ seg++;
+ seg_done = 0;
+ }
+ }
+
+ nr_pages -= bio->bi_vcnt;
+
+ if (dio->rw == READ)
+ bio_set_pages_dirty(bio);
+
+ atomic_long_inc(&dio->refcount);
+ ret = dio_send_bio(dio, sdio, bio, offset + dio->result);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
}

/*
@@ -1041,76 +474,57 @@ static inline int drop_refcount(struct dio *dio)
* individual fields and will generate much worse code. This is important
* for the whole file.
*/
-static inline ssize_t
+static ssize_t
do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
- struct block_device *bdev, const struct iovec *iov, loff_t offset,
+ struct block_device *bdev, const struct iovec *iov, loff_t offset,
unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io,
dio_submit_t submit_io, int flags)
{
- int seg;
- size_t size;
- unsigned long addr;
- unsigned i_blkbits = ACCESS_ONCE(inode->i_blkbits);
- unsigned blkbits = i_blkbits;
- unsigned blocksize_mask = (1 << blkbits) - 1;
- ssize_t retval = -EINVAL;
- loff_t end = offset;
+ unsigned nr_pages = 0, blocksize_mask;
+ size_t size = 0;
+ ssize_t retval = 0;
+ const struct iovec *v;
struct dio *dio;
- struct dio_submit sdio = { 0, };
- unsigned long user_addr;
- size_t bytes;
- struct buffer_head map_bh = { 0, };
+ struct dio_submit sdio;
struct blk_plug plug;

if (rw & WRITE)
rw = WRITE_ODIRECT;

- /*
- * Avoid references to bdev if not absolutely needed to give
- * the early prefetch in the caller enough time.
- */
+ sdio.get_block = get_block;
+ sdio.submit_io = submit_io;
+ sdio.i_blkbits = ACCESS_ONCE(inode->i_blkbits);

- if (offset & blocksize_mask) {
- if (bdev)
- blkbits = blksize_bits(bdev_logical_block_size(bdev));
- blocksize_mask = (1 << blkbits) - 1;
- if (offset & blocksize_mask)
- goto out;
- }
+ for (v = iov; v < iov + nr_segs; v++) {
+ unsigned offset = (size_t) v->iov_base & (PAGE_SIZE - 1);

- /* Check the memory alignment. Blocks cannot straddle pages */
- for (seg = 0; seg < nr_segs; seg++) {
- addr = (unsigned long)iov[seg].iov_base;
- size = iov[seg].iov_len;
- end += size;
- if (unlikely((addr & blocksize_mask) ||
- (size & blocksize_mask))) {
- if (bdev)
- blkbits = blksize_bits(
- bdev_logical_block_size(bdev));
- blocksize_mask = (1 << blkbits) - 1;
- if ((addr & blocksize_mask) || (size & blocksize_mask))
- goto out;
- }
+ nr_pages += DIV_ROUND_UP(offset + v->iov_len, PAGE_SIZE);
+ size += v->iov_len;
}

/* watch out for a 0 len io from a tricksy fs */
- if (rw == READ && end == offset)
+ if (rw == READ && !size)
return 0;

- dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);
- retval = -ENOMEM;
- if (!dio)
- goto out;
+ blocksize_mask = (1 << sdio.i_blkbits) - 1;
+
/*
- * Believe it or not, zeroing out the page array caused a .5%
- * performance regression in a database benchmark. So, we take
- * care to only zero out what's needed.
+ * Avoid references to bdev if not absolutely needed to give
+ * the early prefetch in the caller enough time.
*/
- memset(dio, 0, offsetof(struct dio, pages));

- dio->flags = flags;
- if (dio->flags & DIO_LOCKING) {
+ if (unlikely((offset & blocksize_mask) ||
+ (size & blocksize_mask))) {
+ if (bdev)
+ blocksize_mask = roundup_pow_of_two(
+ bdev_logical_block_size(bdev)) - 1;
+
+ if ((offset & blocksize_mask) ||
+ (size & blocksize_mask))
+ return -EINVAL;
+ }
+
+ if (flags & DIO_LOCKING) {
if (rw == READ) {
struct address_space *mapping =
iocb->ki_filp->f_mapping;
@@ -1119,11 +533,10 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
mutex_lock(&inode->i_mutex);

retval = filemap_write_and_wait_range(mapping, offset,
- end - 1);
+ offset + size - 1);
if (retval) {
mutex_unlock(&inode->i_mutex);
- kmem_cache_free(dio_cache, dio);
- goto out;
+ return retval;
}
}
}
@@ -1133,83 +546,27 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
*/
atomic_inc(&inode->i_dio_count);

- /*
- * For file extending writes updating i_size before data
- * writeouts complete can expose uninitialized blocks. So
- * even for AIO, we need to wait for i/o to complete before
- * returning in this case.
- */
- dio->is_async = !is_sync_kiocb(iocb) && !((rw & WRITE) &&
- (end > i_size_read(inode)));
-
- retval = 0;
-
- dio->inode = inode;
- dio->rw = rw;
- sdio.blkbits = blkbits;
- sdio.blkfactor = i_blkbits - blkbits;
- sdio.block_in_file = offset >> blkbits;
-
- sdio.get_block = get_block;
- dio->end_io = end_io;
- sdio.submit_io = submit_io;
- sdio.final_block_in_bio = -1;
- sdio.next_block_for_io = -1;
-
- dio->iocb = iocb;
- dio->i_size = i_size_read(inode);
-
- spin_lock_init(&dio->bio_lock);
- dio->refcount = 1;
-
- /*
- * In case of non-aligned buffers, we may need 2 more
- * pages since we need to zero out first and last block.
- */
- if (unlikely(sdio.blkfactor))
- sdio.pages_in_io = 2;
-
- for (seg = 0; seg < nr_segs; seg++) {
- user_addr = (unsigned long)iov[seg].iov_base;
- sdio.pages_in_io +=
- ((user_addr + iov[seg].iov_len + PAGE_SIZE-1) /
- PAGE_SIZE - user_addr / PAGE_SIZE);
- }
+ dio = container_of(bio_alloc_bioset(GFP_KERNEL,
+ min_t(unsigned, BIO_MAX_PAGES, nr_pages),
+ dio_pool),
+ struct dio, bio);
+
+ dio->flags = flags;
+ dio->rw = rw;
+ dio->inode = inode;
+ dio->i_size = i_size_read(inode);
+ dio->end_io = end_io;
+ dio->private = NULL;
+ dio->page_error = 0;
+ dio->io_error = 0;
+ atomic_long_set(&dio->refcount, 1);
+ dio->waiter = current;
+ dio->iocb = iocb;
+ dio->result = 0;

blk_start_plug(&plug);

- for (seg = 0; seg < nr_segs; seg++) {
- user_addr = (unsigned long)iov[seg].iov_base;
- sdio.size += bytes = iov[seg].iov_len;
-
- /* Index into the first page of the first block */
- sdio.first_block_in_page = (user_addr & ~PAGE_MASK) >> blkbits;
- sdio.final_block_in_request = sdio.block_in_file +
- (bytes >> blkbits);
- /* Page fetching state */
- sdio.head = 0;
- sdio.tail = 0;
- sdio.curr_page = 0;
-
- sdio.total_pages = 0;
- if (user_addr & (PAGE_SIZE-1)) {
- sdio.total_pages++;
- bytes -= PAGE_SIZE - (user_addr & (PAGE_SIZE - 1));
- }
- sdio.total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
- sdio.curr_user_address = user_addr;
-
- retval = do_direct_IO(dio, &sdio, &map_bh);
-
- dio->result += iov[seg].iov_len -
- ((sdio.final_block_in_request - sdio.block_in_file) <<
- blkbits);
-
- if (retval) {
- dio_cleanup(dio, &sdio);
- break;
- }
- } /* end iovec loop */
+ retval = dio_alloc_bios(dio, &sdio, iov, offset, nr_segs, nr_pages);

if (retval == -ENOTBLK) {
/*
@@ -1218,33 +575,10 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
*/
retval = 0;
}
- /*
- * There may be some unwritten disk at the end of a part-written
- * fs-block-sized block. Go zero that now.
- */
- dio_zero_block(dio, &sdio, 1, &map_bh);
-
- if (sdio.cur_page) {
- ssize_t ret2;
-
- ret2 = dio_send_cur_page(dio, &sdio, &map_bh);
- if (retval == 0)
- retval = ret2;
- page_cache_release(sdio.cur_page);
- sdio.cur_page = NULL;
- }
- if (sdio.bio)
- dio_bio_submit(dio, &sdio);

blk_finish_plug(&plug);

/*
- * It is possible that, we return short IO due to end of file.
- * In that case, we need to release all the pages we got hold on.
- */
- dio_cleanup(dio, &sdio);
-
- /*
* All block lookups have been performed. For READ requests
* we can let i_mutex go now that its achieved its purpose
* of protecting us from looking up uninitialized blocks.
@@ -1260,20 +594,28 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
* This had *better* be the only place that raises -EIOCBQUEUED.
*/
BUG_ON(retval == -EIOCBQUEUED);
- if (dio->is_async && retval == 0 && dio->result &&
- ((rw == READ) || (dio->result == sdio.size)))
- retval = -EIOCBQUEUED;

- if (retval != -EIOCBQUEUED)
- dio_await_completion(dio);
-
- if (drop_refcount(dio) == 0) {
+ /*
+ * For file extending writes updating i_size before data
+ * writeouts complete can expose uninitialized blocks. So
+ * even for AIO, we need to wait for i/o to complete before
+ * returning in this case.
+ */
+ if (!is_sync_kiocb(iocb) &&
+ retval == 0 && dio->result &&
+ ((rw == READ) ||
+ (offset + size <= dio->i_size &&
+ dio->result == size))) {
+ if (atomic_long_dec_and_test(&dio->refcount))
+ retval = dio_complete(dio, offset, retval, false);
+ else
+ retval = -EIOCBQUEUED;
+ } else {
+ dio_wait_completion(dio);
retval = dio_complete(dio, offset, retval, false);
- kmem_cache_free(dio_cache, dio);
- } else
- BUG_ON(retval != -EIOCBQUEUED);
+ BUG_ON(retval == -EIOCBQUEUED);
+ }

-out:
return retval;
}

@@ -1304,7 +646,9 @@ EXPORT_SYMBOL(__blockdev_direct_IO);

static __init int dio_init(void)
{
- dio_cache = KMEM_CACHE(dio, SLAB_PANIC);
+ dio_pool = bioset_create(4, offsetof(struct dio, bio));
+ if (!dio_pool)
+ return -ENOMEM;
return 0;
}
module_init(dio_init)
--
1.8.3.rc1