Merge branch 'next' into for-linus

1 files changed, 337 insertions, 309 deletions

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 44a360ca8046..d740ab67ff6e 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -39,7 +39,7 @@
 
 /*
  * How many user pages to map in one call to get_user_pages().  This determines
- * the size of a structure on the stack.
+ * the size of a structure in the slab cache
  */
 #define DIO_PAGES       64
 
@@ -55,13 +55,10 @@
  * blocksize.
  */
 
-struct dio {
-        /* BIO submission state */
+/* dio_state only used in the submission path */
+
+struct dio_submit {
         struct bio *bio;                /* bio under assembly */
-        struct inode *inode;
-        int rw;
-        loff_t i_size;                  /* i_size when submitted */
-        int flags;                      /* doesn't change */
         unsigned blkbits;               /* doesn't change */
         unsigned blkfactor;             /* When we're using an alignment which
                                            is finer than the filesystem's soft
@@ -76,18 +73,17 @@ struct dio {
         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 */
-        int reap_counter;               /* rate limit reaping */
         get_block_t *get_block;         /* block mapping function */
-        dio_iodone_t *end_io;           /* IO completion 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 */
-        struct buffer_head map_bh;      /* last get_block() result */
 
         /*
          * Deferred addition of a page to the dio.  These variables are
@@ -100,18 +96,6 @@ struct dio {
         sector_t cur_page_block;        /* Where it starts */
         loff_t cur_page_fs_offset;      /* Offset in file */
 
-        /* BIO completion state */
-        spinlock_t bio_lock;            /* protects BIO fields below */
-        unsigned long refcount;         /* direct_io_worker() and bios */
-        struct bio *bio_list;           /* singly linked via bi_private */
-        struct task_struct *waiter;     /* waiting task (NULL if none) */
-
-        /* AIO related stuff */
-        struct kiocb *iocb;             /* kiocb */
-        int is_async;                   /* is IO async ? */
-        int io_error;                   /* IO error in completion path */
-        ssize_t result;                 /* IO result */
-
         /*
          * Page fetching state. These variables belong to dio_refill_pages().
          */
@@ -125,7 +109,30 @@ struct dio {
          */
         unsigned head;                  /* next page to process */
         unsigned tail;                  /* last valid page + 1 */
+};
+
+/* 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 */
+
+        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 */
+        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
@@ -133,7 +140,9 @@ struct dio {
          * wish that they not be zeroed.
          */
         struct page *pages[DIO_PAGES];  /* page buffer */
-};
+} ____cacheline_aligned_in_smp;
+
+static struct kmem_cache *dio_cache __read_mostly;
 
 static void __inode_dio_wait(struct inode *inode)
 {
@@ -182,27 +191,27 @@ EXPORT_SYMBOL_GPL(inode_dio_done);
 /*
  * How many pages are in the queue?
  */
-static inline unsigned dio_pages_present(struct dio *dio)
+static inline unsigned dio_pages_present(struct dio_submit *sdio)
 {
-        return dio->tail - dio->head;
+        return sdio->tail - sdio->head;
 }
 
 /*
  * Go grab and pin some userspace pages.   Typically we'll get 64 at a time.
  */
-static int dio_refill_pages(struct dio *dio)
+static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)
 {
         int ret;
         int nr_pages;
 
-        nr_pages = min(dio->total_pages - dio->curr_page, DIO_PAGES);
+        nr_pages = min(sdio->total_pages - sdio->curr_page, DIO_PAGES);
         ret = get_user_pages_fast(
-                dio->curr_user_address,         /* Where from? */
+                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 && dio->blocks_available && (dio->rw & WRITE)) {
+        if (ret < 0 && sdio->blocks_available && (dio->rw & WRITE)) {
                 struct page *page = ZERO_PAGE(0);
                 /*
                  * A memory fault, but the filesystem has some outstanding
@@ -213,17 +222,17 @@ static int dio_refill_pages(struct dio *dio)
                         dio->page_errors = ret;
                 page_cache_get(page);
                 dio->pages[0] = page;
-                dio->head = 0;
-                dio->tail = 1;
+                sdio->head = 0;
+                sdio->tail = 1;
                 ret = 0;
                 goto out;
         }
 
         if (ret >= 0) {
-                dio->curr_user_address += ret * PAGE_SIZE;
-                dio->curr_page += ret;
-                dio->head = 0;
-                dio->tail = ret;
+                sdio->curr_user_address += ret * PAGE_SIZE;
+                sdio->curr_page += ret;
+                sdio->head = 0;
+                sdio->tail = ret;
                 ret = 0;
         }
 out:
@@ -236,17 +245,18 @@ out:
  * decent number of pages, less frequently.  To provide nicer use of the
  * L1 cache.
  */
-static struct page *dio_get_page(struct dio *dio)
+static inline struct page *dio_get_page(struct dio *dio,
+                struct dio_submit *sdio)
 {
-        if (dio_pages_present(dio) == 0) {
+        if (dio_pages_present(sdio) == 0) {
                 int ret;
 
-                ret = dio_refill_pages(dio);
+                ret = dio_refill_pages(dio, sdio);
                 if (ret)
                         return ERR_PTR(ret);
-                BUG_ON(dio_pages_present(dio) == 0);
+                BUG_ON(dio_pages_present(sdio) == 0);
         }
-        return dio->pages[dio->head++];
+        return dio->pages[sdio->head++];
 }
 
 /**
@@ -292,7 +302,7 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is
 
         if (dio->end_io && dio->result) {
                 dio->end_io(dio->iocb, offset, transferred,
-                            dio->map_bh.b_private, ret, is_async);
+                            dio->private, ret, is_async);
         } else {
                 if (is_async)
                         aio_complete(dio->iocb, ret, 0);
@@ -323,7 +333,7 @@ static void dio_bio_end_aio(struct bio *bio, int error)
 
         if (remaining == 0) {
                 dio_complete(dio, dio->iocb->ki_pos, 0, true);
-                kfree(dio);
+                kmem_cache_free(dio_cache, dio);
         }
 }
 
@@ -367,9 +377,10 @@ void dio_end_io(struct bio *bio, int error)
 }
 EXPORT_SYMBOL_GPL(dio_end_io);
 
-static void
-dio_bio_alloc(struct dio *dio, struct block_device *bdev,
-                sector_t first_sector, int nr_vecs)
+static inline void
+dio_bio_alloc(struct dio *dio, struct dio_submit *sdio,
+              struct block_device *bdev,
+              sector_t first_sector, int nr_vecs)
 {
         struct bio *bio;
 
@@ -386,8 +397,8 @@ dio_bio_alloc(struct dio *dio, struct block_device *bdev,
         else
                 bio->bi_end_io = dio_bio_end_io;
 
-        dio->bio = bio;
-        dio->logical_offset_in_bio = dio->cur_page_fs_offset;
+        sdio->bio = bio;
+        sdio->logical_offset_in_bio = sdio->cur_page_fs_offset;
 }
 
 /*
@@ -397,9 +408,9 @@ dio_bio_alloc(struct dio *dio, struct block_device *bdev,
  *
  * bios hold a dio reference between submit_bio and ->end_io.
  */
-static void dio_bio_submit(struct dio *dio)
+static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)
 {
-        struct bio *bio = dio->bio;
+        struct bio *bio = sdio->bio;
         unsigned long flags;
 
         bio->bi_private = dio;
@@ -411,24 +422,24 @@ static void dio_bio_submit(struct dio *dio)
         if (dio->is_async && dio->rw == READ)
                 bio_set_pages_dirty(bio);
 
-        if (dio->submit_io)
-                dio->submit_io(dio->rw, bio, dio->inode,
-                               dio->logical_offset_in_bio);
+        if (sdio->submit_io)
+                sdio->submit_io(dio->rw, bio, dio->inode,
+                               sdio->logical_offset_in_bio);
         else
                 submit_bio(dio->rw, bio);
 
-        dio->bio = NULL;
-        dio->boundary = 0;
-        dio->logical_offset_in_bio = 0;
+        sdio->bio = NULL;
+        sdio->boundary = 0;
+        sdio->logical_offset_in_bio = 0;
 }
 
 /*
  * Release any resources in case of a failure
  */
-static void dio_cleanup(struct dio *dio)
+static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio)
 {
-        while (dio_pages_present(dio))
-                page_cache_release(dio_get_page(dio));
+        while (dio_pages_present(sdio))
+                page_cache_release(dio_get_page(dio, sdio));
 }
 
 /*
@@ -518,11 +529,11 @@ static void dio_await_completion(struct dio *dio)
  *
  * This also helps to limit the peak amount of pinned userspace memory.
  */
-static int dio_bio_reap(struct dio *dio)
+static inline int dio_bio_reap(struct dio *dio, struct dio_submit *sdio)
 {
         int ret = 0;
 
-        if (dio->reap_counter++ >= 64) {
+        if (sdio->reap_counter++ >= 64) {
                 while (dio->bio_list) {
                         unsigned long flags;
                         struct bio *bio;
@@ -536,14 +547,14 @@ static int dio_bio_reap(struct dio *dio)
                         if (ret == 0)
                                 ret = ret2;
                 }
-                dio->reap_counter = 0;
+                sdio->reap_counter = 0;
         }
         return ret;
 }
 
 /*
  * Call into the fs to map some more disk blocks.  We record the current number
- * of available blocks at dio->blocks_available.  These are in units of the
+ * 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,
@@ -564,10 +575,10 @@ static int dio_bio_reap(struct dio *dio)
  * 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)
+static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
+                           struct buffer_head *map_bh)
 {
         int ret;
-        struct buffer_head *map_bh = &dio->map_bh;
         sector_t fs_startblk;   /* Into file, in filesystem-sized blocks */
         unsigned long fs_count; /* Number of filesystem-sized blocks */
         unsigned long dio_count;/* Number of dio_block-sized blocks */
@@ -580,11 +591,11 @@ static int get_more_blocks(struct dio *dio)
          */
         ret = dio->page_errors;
         if (ret == 0) {
-                BUG_ON(dio->block_in_file >= dio->final_block_in_request);
-                fs_startblk = dio->block_in_file >> dio->blkfactor;
-                dio_count = dio->final_block_in_request - dio->block_in_file;
-                fs_count = dio_count >> dio->blkfactor;
-                blkmask = (1 << dio->blkfactor) - 1;
+                BUG_ON(sdio->block_in_file >= sdio->final_block_in_request);
+                fs_startblk = sdio->block_in_file >> sdio->blkfactor;
+                dio_count = sdio->final_block_in_request - sdio->block_in_file;
+                fs_count = dio_count >> sdio->blkfactor;
+                blkmask = (1 << sdio->blkfactor) - 1;
                 if (dio_count & blkmask)        
                         fs_count++;
 
@@ -604,13 +615,16 @@ static int get_more_blocks(struct dio *dio)
                  */
                 create = dio->rw & WRITE;
                 if (dio->flags & DIO_SKIP_HOLES) {
-                        if (dio->block_in_file < (i_size_read(dio->inode) >>
-                                                        dio->blkbits))
+                        if (sdio->block_in_file < (i_size_read(dio->inode) >>
+                                                        sdio->blkbits))
                                 create = 0;
                 }
 
-                ret = (*dio->get_block)(dio->inode, fs_startblk,
+                ret = (*sdio->get_block)(dio->inode, fs_startblk,
                                                 map_bh, create);
+
+                /* Store for completion */
+                dio->private = map_bh->b_private;
         }
         return ret;
 }
@@ -618,20 +632,21 @@ static int get_more_blocks(struct dio *dio)
 /*
  * There is no bio.  Make one now.
  */
-static int dio_new_bio(struct dio *dio, sector_t start_sector)
+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;
 
-        ret = dio_bio_reap(dio);
+        ret = dio_bio_reap(dio, sdio);
         if (ret)
                 goto out;
-        sector = start_sector << (dio->blkbits - 9);
-        nr_pages = min(dio->pages_in_io, bio_get_nr_vecs(dio->map_bh.b_bdev));
+        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, dio->map_bh.b_bdev, sector, nr_pages);
-        dio->boundary = 0;
+        dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages);
+        sdio->boundary = 0;
 out:
         return ret;
 }
@@ -643,21 +658,21 @@ out:
  *
  * Return zero on success.  Non-zero means the caller needs to start a new BIO.
  */
-static int dio_bio_add_page(struct dio *dio)
+static inline int dio_bio_add_page(struct dio_submit *sdio)
 {
         int ret;
 
-        ret = bio_add_page(dio->bio, dio->cur_page,
-                        dio->cur_page_len, dio->cur_page_offset);
-        if (ret == dio->cur_page_len) {
+        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 ((dio->cur_page_len + dio->cur_page_offset) == PAGE_SIZE)
-                        dio->pages_in_io--;
-                page_cache_get(dio->cur_page);
-                dio->final_block_in_bio = dio->cur_page_block +
-                        (dio->cur_page_len >> dio->blkbits);
+                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;
@@ -675,14 +690,15 @@ static int dio_bio_add_page(struct dio *dio)
  * 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 int dio_send_cur_page(struct dio *dio)
+static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,
+                struct buffer_head *map_bh)
 {
         int ret = 0;
 
-        if (dio->bio) {
-                loff_t cur_offset = dio->cur_page_fs_offset;
-                loff_t bio_next_offset = dio->logical_offset_in_bio +
-                        dio->bio->bi_size;
+        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_size;
 
                 /*
                  * See whether this new request is contiguous with the old.
@@ -698,28 +714,28 @@ static int dio_send_cur_page(struct dio *dio)
                  * be the next logical offset in the bio, submit the bio we
                  * have.
                  */
-                if (dio->final_block_in_bio != dio->cur_page_block ||
+                if (sdio->final_block_in_bio != sdio->cur_page_block ||
                     cur_offset != bio_next_offset)
-                        dio_bio_submit(dio);
+                        dio_bio_submit(dio, sdio);
                 /*
                  * Submit now if the underlying fs is about to perform a
                  * metadata read
                  */
-                else if (dio->boundary)
-                        dio_bio_submit(dio);
+                else if (sdio->boundary)
+                        dio_bio_submit(dio, sdio);
         }
 
-        if (dio->bio == NULL) {
-                ret = dio_new_bio(dio, dio->cur_page_block);
+        if (sdio->bio == NULL) {
+                ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh);
                 if (ret)
                         goto out;
         }
 
-        if (dio_bio_add_page(dio) != 0) {
-                dio_bio_submit(dio);
-                ret = dio_new_bio(dio, dio->cur_page_block);
+        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(dio);
+                        ret = dio_bio_add_page(sdio);
                         BUG_ON(ret != 0);
                 }
         }
@@ -744,9 +760,10 @@ out:
  * If that doesn't work out then we put the old page into the bio and add this
  * page to the dio instead.
  */
-static int
-submit_page_section(struct dio *dio, struct page *page,
-                unsigned offset, unsigned len, sector_t blocknr)
+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)
 {
         int ret = 0;
 
@@ -760,20 +777,20 @@ submit_page_section(struct dio *dio, struct page *page,
         /*
          * Can we just grow the current page's presence in the dio?
          */
-        if (    (dio->cur_page == page) &&
-                (dio->cur_page_offset + dio->cur_page_len == offset) &&
-                (dio->cur_page_block +
-                        (dio->cur_page_len >> dio->blkbits) == blocknr)) {
-                dio->cur_page_len += len;
+        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;
 
                 /*
-                 * If dio->boundary then we want to schedule the IO now to
+                 * If sdio->boundary then we want to schedule the IO now to
                  * avoid metadata seeks.
                  */
-                if (dio->boundary) {
-                        ret = dio_send_cur_page(dio);
-                        page_cache_release(dio->cur_page);
-                        dio->cur_page = NULL;
+                if (sdio->boundary) {
+                        ret = dio_send_cur_page(dio, sdio, map_bh);
+                        page_cache_release(sdio->cur_page);
+                        sdio->cur_page = NULL;
                 }
                 goto out;
         }
@@ -781,20 +798,20 @@ submit_page_section(struct dio *dio, struct page *page,
         /*
          * If there's a deferred page already there then send it.
          */
-        if (dio->cur_page) {
-                ret = dio_send_cur_page(dio);
-                page_cache_release(dio->cur_page);
-                dio->cur_page = NULL;
+        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)
                         goto out;
         }
 
         page_cache_get(page);           /* It is in dio */
-        dio->cur_page = page;
-        dio->cur_page_offset = offset;
-        dio->cur_page_len = len;
-        dio->cur_page_block = blocknr;
-        dio->cur_page_fs_offset = dio->block_in_file << dio->blkbits;
+        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:
         return ret;
 }
@@ -804,16 +821,16 @@ out:
  * file blocks.  Only called for S_ISREG files - blockdevs do not set
  * buffer_new
  */
-static void clean_blockdev_aliases(struct dio *dio)
+static void clean_blockdev_aliases(struct dio *dio, struct buffer_head *map_bh)
 {
         unsigned i;
         unsigned nblocks;
 
-        nblocks = dio->map_bh.b_size >> dio->inode->i_blkbits;
+        nblocks = map_bh->b_size >> dio->inode->i_blkbits;
 
         for (i = 0; i < nblocks; i++) {
-                unmap_underlying_metadata(dio->map_bh.b_bdev,
-                                        dio->map_bh.b_blocknr + i);
+                unmap_underlying_metadata(map_bh->b_bdev,
+                                          map_bh->b_blocknr + i);
         }
 }
 
@@ -826,19 +843,20 @@ static void clean_blockdev_aliases(struct dio *dio)
  * `end' is zero if we're doing the start of the IO, 1 at the end of the
  * IO.
  */
-static void dio_zero_block(struct dio *dio, int end)
+static inline void dio_zero_block(struct dio *dio, struct dio_submit *sdio,
+                int end, struct buffer_head *map_bh)
 {
         unsigned dio_blocks_per_fs_block;
         unsigned this_chunk_blocks;     /* In dio_blocks */
         unsigned this_chunk_bytes;
         struct page *page;
 
-        dio->start_zero_done = 1;
-        if (!dio->blkfactor || !buffer_new(&dio->map_bh))
+        sdio->start_zero_done = 1;
+        if (!sdio->blkfactor || !buffer_new(map_bh))
                 return;
 
-        dio_blocks_per_fs_block = 1 << dio->blkfactor;
-        this_chunk_blocks = dio->block_in_file & (dio_blocks_per_fs_block - 1);
+        dio_blocks_per_fs_block = 1 << sdio->blkfactor;
+        this_chunk_blocks = sdio->block_in_file & (dio_blocks_per_fs_block - 1);
 
         if (!this_chunk_blocks)
                 return;
@@ -850,14 +868,14 @@ static void dio_zero_block(struct dio *dio, int end)
         if (end) 
                 this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks;
 
-        this_chunk_bytes = this_chunk_blocks << dio->blkbits;
+        this_chunk_bytes = this_chunk_blocks << sdio->blkbits;
 
         page = ZERO_PAGE(0);
-        if (submit_page_section(dio, page, 0, this_chunk_bytes, 
-                                dio->next_block_for_io))
+        if (submit_page_section(dio, sdio, page, 0, this_chunk_bytes,
+                                sdio->next_block_for_io, map_bh))
                 return;
 
-        dio->next_block_for_io += this_chunk_blocks;
+        sdio->next_block_for_io += this_chunk_blocks;
 }
 
 /*
@@ -876,20 +894,20 @@ static void dio_zero_block(struct dio *dio, int end)
  * 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)
+static int do_direct_IO(struct dio *dio, struct dio_submit *sdio,
+                        struct buffer_head *map_bh)
 {
-        const unsigned blkbits = dio->blkbits;
+        const unsigned blkbits = sdio->blkbits;
         const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
         struct page *page;
         unsigned block_in_page;
-        struct buffer_head *map_bh = &dio->map_bh;
         int ret = 0;
 
         /* The I/O can start at any block offset within the first page */
-        block_in_page = dio->first_block_in_page;
+        block_in_page = sdio->first_block_in_page;
 
-        while (dio->block_in_file < dio->final_block_in_request) {
-                page = dio_get_page(dio);
+        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;
@@ -901,14 +919,14 @@ static int do_direct_IO(struct dio *dio)
                         unsigned this_chunk_blocks;     /* # of blocks */
                         unsigned u;
 
-                        if (dio->blocks_available == 0) {
+                        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);
+                                ret = get_more_blocks(dio, sdio, map_bh);
                                 if (ret) {
                                         page_cache_release(page);
                                         goto out;
@@ -916,18 +934,18 @@ static int do_direct_IO(struct dio *dio)
                                 if (!buffer_mapped(map_bh))
                                         goto do_holes;
 
-                                dio->blocks_available =
-                                                map_bh->b_size >> dio->blkbits;
-                                dio->next_block_for_io =
-                                        map_bh->b_blocknr << dio->blkfactor;
+                                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);
+                                        clean_blockdev_aliases(dio, map_bh);
 
-                                if (!dio->blkfactor)
+                                if (!sdio->blkfactor)
                                         goto do_holes;
 
-                                blkmask = (1 << dio->blkfactor) - 1;
-                                dio_remainder = (dio->block_in_file & blkmask);
+                                blkmask = (1 << sdio->blkfactor) - 1;
+                                dio_remainder = (sdio->block_in_file & blkmask);
 
                                 /*
                                  * If we are at the start of IO and that IO
@@ -941,8 +959,8 @@ static int do_direct_IO(struct dio *dio)
                                  * on-disk
                                  */
                                 if (!buffer_new(map_bh))
-                                        dio->next_block_for_io += dio_remainder;
-                                dio->blocks_available -= dio_remainder;
+                                        sdio->next_block_for_io += dio_remainder;
+                                sdio->blocks_available -= dio_remainder;
                         }
 do_holes:
                         /* Handle holes */
@@ -961,7 +979,7 @@ do_holes:
                                  */
                                 i_size_aligned = ALIGN(i_size_read(dio->inode),
                                                         1 << blkbits);
-                                if (dio->block_in_file >=
+                                if (sdio->block_in_file >=
                                                 i_size_aligned >> blkbits) {
                                         /* We hit eof */
                                         page_cache_release(page);
@@ -969,7 +987,7 @@ do_holes:
                                 }
                                 zero_user(page, block_in_page << blkbits,
                                                 1 << blkbits);
-                                dio->block_in_file++;
+                                sdio->block_in_file++;
                                 block_in_page++;
                                 goto next_block;
                         }
@@ -979,38 +997,41 @@ do_holes:
                          * is finer than the underlying fs, go check to see if
                          * we must zero out the start of this block.
                          */
-                        if (unlikely(dio->blkfactor && !dio->start_zero_done))
-                                dio_zero_block(dio, 0);
+                        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 = dio->blocks_available;
+                        this_chunk_blocks = sdio->blocks_available;
                         u = (PAGE_SIZE - offset_in_page) >> blkbits;
                         if (this_chunk_blocks > u)
                                 this_chunk_blocks = u;
-                        u = dio->final_block_in_request - dio->block_in_file;
+                        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);
 
-                        dio->boundary = buffer_boundary(map_bh);
-                        ret = submit_page_section(dio, page, offset_in_page,
-                                this_chunk_bytes, dio->next_block_for_io);
+                        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;
                         }
-                        dio->next_block_for_io += this_chunk_blocks;
+                        sdio->next_block_for_io += this_chunk_blocks;
 
-                        dio->block_in_file += this_chunk_blocks;
+                        sdio->block_in_file += this_chunk_blocks;
                         block_in_page += this_chunk_blocks;
-                        dio->blocks_available -= this_chunk_blocks;
+                        sdio->blocks_available -= this_chunk_blocks;
 next_block:
-                        BUG_ON(dio->block_in_file > dio->final_block_in_request);
-                        if (dio->block_in_file == dio->final_block_in_request)
+                        BUG_ON(sdio->block_in_file > sdio->final_block_in_request);
+                        if (sdio->block_in_file == sdio->final_block_in_request)
                                 break;
                 }
 
@@ -1022,135 +1043,10 @@ out:
         return ret;
 }
 
-static ssize_t
-direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, 
-        const struct iovec *iov, loff_t offset, unsigned long nr_segs, 
-        unsigned blkbits, get_block_t get_block, dio_iodone_t end_io,
-        dio_submit_t submit_io, struct dio *dio)
+static inline int drop_refcount(struct dio *dio)
 {
-        unsigned long user_addr; 
+        int ret2;
         unsigned long flags;
-        int seg;
-        ssize_t ret = 0;
-        ssize_t ret2;
-        size_t bytes;
-
-        dio->inode = inode;
-        dio->rw = rw;
-        dio->blkbits = blkbits;
-        dio->blkfactor = inode->i_blkbits - blkbits;
-        dio->block_in_file = offset >> blkbits;
-
-        dio->get_block = get_block;
-        dio->end_io = end_io;
-        dio->submit_io = submit_io;
-        dio->final_block_in_bio = -1;
-        dio->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(dio->blkfactor))
-                dio->pages_in_io = 2;
-
-        for (seg = 0; seg < nr_segs; seg++) {
-                user_addr = (unsigned long)iov[seg].iov_base;
-                dio->pages_in_io +=
-                        ((user_addr+iov[seg].iov_len +PAGE_SIZE-1)/PAGE_SIZE
-                                - user_addr/PAGE_SIZE);
-        }
-
-        for (seg = 0; seg < nr_segs; seg++) {
-                user_addr = (unsigned long)iov[seg].iov_base;
-                dio->size += bytes = iov[seg].iov_len;
-
-                /* Index into the first page of the first block */
-                dio->first_block_in_page = (user_addr & ~PAGE_MASK) >> blkbits;
-                dio->final_block_in_request = dio->block_in_file +
-                                                (bytes >> blkbits);
-                /* Page fetching state */
-                dio->head = 0;
-                dio->tail = 0;
-                dio->curr_page = 0;
-
-                dio->total_pages = 0;
-                if (user_addr & (PAGE_SIZE-1)) {
-                        dio->total_pages++;
-                        bytes -= PAGE_SIZE - (user_addr & (PAGE_SIZE - 1));
-                }
-                dio->total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
-                dio->curr_user_address = user_addr;
-        
-                ret = do_direct_IO(dio);
-
-                dio->result += iov[seg].iov_len -
-                        ((dio->final_block_in_request - dio->block_in_file) <<
-                                        blkbits);
-
-                if (ret) {
-                        dio_cleanup(dio);
-                        break;
-                }
-        } /* end iovec loop */
-
-        if (ret == -ENOTBLK) {
-                /*
-                 * The remaining part of the request will be
-                 * be handled by buffered I/O when we return
-                 */
-                ret = 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, 1);
-
-        if (dio->cur_page) {
-                ret2 = dio_send_cur_page(dio);
-                if (ret == 0)
-                        ret = ret2;
-                page_cache_release(dio->cur_page);
-                dio->cur_page = NULL;
-        }
-        if (dio->bio)
-                dio_bio_submit(dio);
-
-        /*
-         * 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);
-
-        /*
-         * 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.
-         */
-        if (rw == READ && (dio->flags & DIO_LOCKING))
-                mutex_unlock(&dio->inode->i_mutex);
-
-        /*
-         * The only time we want to leave bios in flight is when a successful
-         * partial aio read or full aio write have been setup.  In that case
-         * bio completion will call aio_complete.  The only time it's safe to
-         * call aio_complete is when we return -EIOCBQUEUED, so we key on that.
-         * This had *better* be the only place that raises -EIOCBQUEUED.
-         */
-        BUG_ON(ret == -EIOCBQUEUED);
-        if (dio->is_async && ret == 0 && dio->result &&
-            ((rw & READ) || (dio->result == dio->size)))
-                ret = -EIOCBQUEUED;
-
-        if (ret != -EIOCBQUEUED)
-                dio_await_completion(dio);
 
         /*
          * Sync will always be dropping the final ref and completing the
@@ -1166,14 +1062,7 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
         spin_lock_irqsave(&dio->bio_lock, flags);
         ret2 = --dio->refcount;
         spin_unlock_irqrestore(&dio->bio_lock, flags);
-
-        if (ret2 == 0) {
-                ret = dio_complete(dio, offset, ret, false);
-                kfree(dio);
-        } else
-                BUG_ON(ret != -EIOCBQUEUED);
-
-        return ret;
+        return ret2;
 }
 
 /*
@@ -1195,6 +1084,11 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
  * expected that filesystem provide exclusion between new direct I/O
  * and truncates.  For DIO_LOCKING filesystems this is done by i_mutex,
  * but other filesystems need to take care of this on their own.
+ *
+ * NOTE: if you pass "sdio" to anything by pointer make sure that function
+ * is always inlined. Otherwise gcc is unable to split the structure into
+ * individual fields and will generate much worse code. This is important
+ * for the whole file.
  */
 ssize_t
 __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
@@ -1211,6 +1105,10 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
         ssize_t retval = -EINVAL;
         loff_t end = offset;
         struct dio *dio;
+        struct dio_submit sdio = { 0, };
+        unsigned long user_addr;
+        size_t bytes;
+        struct buffer_head map_bh = { 0, };
 
         if (rw & WRITE)
                 rw = WRITE_ODIRECT;
@@ -1244,7 +1142,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
         if (rw == READ && end == offset)
                 return 0;
 
-        dio = kmalloc(sizeof(*dio), GFP_KERNEL);
+        dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);
         retval = -ENOMEM;
         if (!dio)
                 goto out;
@@ -1268,7 +1166,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
                                                               end - 1);
                         if (retval) {
                                 mutex_unlock(&inode->i_mutex);
-                                kfree(dio);
+                                kmem_cache_free(dio_cache, dio);
                                 goto out;
                         }
                 }
@@ -1288,11 +1186,141 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
         dio->is_async = !is_sync_kiocb(iocb) && !((rw & WRITE) &&
                 (end > i_size_read(inode)));
 
-        retval = direct_io_worker(rw, iocb, inode, iov, offset,
-                                nr_segs, blkbits, get_block, end_io,
-                                submit_io, dio);
+        retval = 0;
+
+        dio->inode = inode;
+        dio->rw = rw;
+        sdio.blkbits = blkbits;
+        sdio.blkfactor = inode->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);
+        }
+
+        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 */
+
+        if (retval == -ENOTBLK) {
+                /*
+                 * The remaining part of the request will be
+                 * be handled by buffered I/O when we return
+                 */
+                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);
+
+        /*
+         * 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.
+         */
+        if (rw == READ && (dio->flags & DIO_LOCKING))
+                mutex_unlock(&dio->inode->i_mutex);
+
+        /*
+         * The only time we want to leave bios in flight is when a successful
+         * partial aio read or full aio write have been setup.  In that case
+         * bio completion will call aio_complete.  The only time it's safe to
+         * call aio_complete is when we return -EIOCBQUEUED, so we key on that.
+         * 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) {
+                retval = dio_complete(dio, offset, retval, false);
+                kmem_cache_free(dio_cache, dio);
+        } else
+                BUG_ON(retval != -EIOCBQUEUED);
 
 out:
         return retval;
 }
 EXPORT_SYMBOL(__blockdev_direct_IO);
+
+static __init int dio_init(void)
+{
+        dio_cache = KMEM_CACHE(dio, SLAB_PANIC);
+        return 0;
+}
+module_init(dio_init)