4 files changed, 185 insertions, 5 deletions

diff --git a/include/linux/bio.h b/include/linux/bio.h
index b900d2c67d29..b89cf2d82898 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -504,6 +504,115 @@ static inline int bio_has_data(struct bio *bio)
         return bio && bio->bi_io_vec != NULL;
 }
 
+/*
+ * BIO list managment for use by remapping drivers (e.g. DM or MD).
+ *
+ * A bio_list anchors a singly-linked list of bios chained through the bi_next
+ * member of the bio.  The bio_list also caches the last list member to allow
+ * fast access to the tail.
+ */
+struct bio_list {
+        struct bio *head;
+        struct bio *tail;
+};
+
+static inline int bio_list_empty(const struct bio_list *bl)
+{
+        return bl->head == NULL;
+}
+
+static inline void bio_list_init(struct bio_list *bl)
+{
+        bl->head = bl->tail = NULL;
+}
+
+#define bio_list_for_each(bio, bl) \
+        for (bio = (bl)->head; bio; bio = bio->bi_next)
+
+static inline unsigned bio_list_size(const struct bio_list *bl)
+{
+        unsigned sz = 0;
+        struct bio *bio;
+
+        bio_list_for_each(bio, bl)
+                sz++;
+
+        return sz;
+}
+
+static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
+{
+        bio->bi_next = NULL;
+
+        if (bl->tail)
+                bl->tail->bi_next = bio;
+        else
+                bl->head = bio;
+
+        bl->tail = bio;
+}
+
+static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
+{
+        bio->bi_next = bl->head;
+
+        bl->head = bio;
+
+        if (!bl->tail)
+                bl->tail = bio;
+}
+
+static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
+{
+        if (!bl2->head)
+                return;
+
+        if (bl->tail)
+                bl->tail->bi_next = bl2->head;
+        else
+                bl->head = bl2->head;
+
+        bl->tail = bl2->tail;
+}
+
+static inline void bio_list_merge_head(struct bio_list *bl,
+                                       struct bio_list *bl2)
+{
+        if (!bl2->head)
+                return;
+
+        if (bl->head)
+                bl2->tail->bi_next = bl->head;
+        else
+                bl->tail = bl2->tail;
+
+        bl->head = bl2->head;
+}
+
+static inline struct bio *bio_list_pop(struct bio_list *bl)
+{
+        struct bio *bio = bl->head;
+
+        if (bio) {
+                bl->head = bl->head->bi_next;
+                if (!bl->head)
+                        bl->tail = NULL;
+
+                bio->bi_next = NULL;
+        }
+
+        return bio;
+}
+
+static inline struct bio *bio_list_get(struct bio_list *bl)
+{
+        struct bio *bio = bl->head;
+
+        bl->head = bl->tail = NULL;
+
+        return bio;
+}
+
 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 
 #define bip_vec_idx(bip, idx)   (&(bip->bip_vec[(idx)]))
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 562d2855cf30..e766be0d4329 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -87,6 +87,60 @@ struct inodes_stat_t {
  */
 #define FMODE_NOCMTIME          ((__force fmode_t)2048)
 
+/*
+ * The below are the various read and write types that we support. Some of
+ * them include behavioral modifiers that send information down to the
+ * block layer and IO scheduler. Terminology:
+ *
+ *      The block layer uses device plugging to defer IO a little bit, in
+ *      the hope that we will see more IO very shortly. This increases
+ *      coalescing of adjacent IO and thus reduces the number of IOs we
+ *      have to send to the device. It also allows for better queuing,
+ *      if the IO isn't mergeable. If the caller is going to be waiting
+ *      for the IO, then he must ensure that the device is unplugged so
+ *      that the IO is dispatched to the driver.
+ *
+ *      All IO is handled async in Linux. This is fine for background
+ *      writes, but for reads or writes that someone waits for completion
+ *      on, we want to notify the block layer and IO scheduler so that they
+ *      know about it. That allows them to make better scheduling
+ *      decisions. So when the below references 'sync' and 'async', it
+ *      is referencing this priority hint.
+ *
+ * With that in mind, the available types are:
+ *
+ * READ                 A normal read operation. Device will be plugged.
+ * READ_SYNC            A synchronous read. Device is not plugged, caller can
+ *                      immediately wait on this read without caring about
+ *                      unplugging.
+ * READA                Used for read-ahead operations. Lower priority, and the
+ *                       block layer could (in theory) choose to ignore this
+ *                      request if it runs into resource problems.
+ * WRITE                A normal async write. Device will be plugged.
+ * SWRITE               Like WRITE, but a special case for ll_rw_block() that
+ *                      tells it to lock the buffer first. Normally a buffer
+ *                      must be locked before doing IO.
+ * WRITE_SYNC_PLUG      Synchronous write. Identical to WRITE, but passes down
+ *                      the hint that someone will be waiting on this IO
+ *                      shortly. The device must still be unplugged explicitly,
+ *                      WRITE_SYNC_PLUG does not do this as we could be
+ *                      submitting more writes before we actually wait on any
+ *                      of them.
+ * WRITE_SYNC           Like WRITE_SYNC_PLUG, but also unplugs the device
+ *                      immediately after submission. The write equivalent
+ *                      of READ_SYNC.
+ * WRITE_ODIRECT        Special case write for O_DIRECT only.
+ * SWRITE_SYNC
+ * SWRITE_SYNC_PLUG     Like WRITE_SYNC/WRITE_SYNC_PLUG, but locks the buffer.
+ *                      See SWRITE.
+ * WRITE_BARRIER        Like WRITE, but tells the block layer that all
+ *                      previously submitted writes must be safely on storage
+ *                      before this one is started. Also guarantees that when
+ *                      this write is complete, it itself is also safely on
+ *                      storage. Prevents reordering of writes on both sides
+ *                      of this IO.
+ *
+ */
 #define RW_MASK         1
 #define RWA_MASK        2
 #define READ 0
@@ -102,6 +156,11 @@ struct inodes_stat_t {
                         (SWRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_NOIDLE))
 #define SWRITE_SYNC     (SWRITE_SYNC_PLUG | (1 << BIO_RW_UNPLUG))
 #define WRITE_BARRIER   (WRITE | (1 << BIO_RW_BARRIER))
+
+/*
+ * These aren't really reads or writes, they pass down information about
+ * parts of device that are now unused by the file system.
+ */
 #define DISCARD_NOBARRIER (1 << BIO_RW_DISCARD)
 #define DISCARD_BARRIER ((1 << BIO_RW_DISCARD) | (1 << BIO_RW_BARRIER))
 
@@ -738,9 +797,6 @@ enum inode_i_mutex_lock_class
         I_MUTEX_QUOTA
 };
 
-extern void inode_double_lock(struct inode *inode1, struct inode *inode2);
-extern void inode_double_unlock(struct inode *inode1, struct inode *inode2);
-
 /*
  * NOTE: in a 32bit arch with a preemptable kernel and
  * an UP compile the i_size_read/write must be atomic
@@ -2150,8 +2206,6 @@ extern ssize_t generic_file_splice_read(struct file *, loff_t *,
                 struct pipe_inode_info *, size_t, unsigned int);
 extern ssize_t generic_file_splice_write(struct pipe_inode_info *,
                 struct file *, loff_t *, size_t, unsigned int);
-extern ssize_t generic_file_splice_write_nolock(struct pipe_inode_info *,
-                struct file *, loff_t *, size_t, unsigned int);
 extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
                 struct file *out, loff_t *, size_t len, unsigned int flags);
 extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 8e4120285f72..c8f038554e80 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -134,6 +134,11 @@ struct pipe_buf_operations {
    memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
 #define PIPE_SIZE               PAGE_SIZE
 
+/* Pipe lock and unlock operations */
+void pipe_lock(struct pipe_inode_info *);
+void pipe_unlock(struct pipe_inode_info *);
+void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
+
 /* Drop the inode semaphore and wait for a pipe event, atomically */
 void pipe_wait(struct pipe_inode_info *pipe);
 
diff --git a/include/linux/splice.h b/include/linux/splice.h
index 528dcb93c2f2..5f3faa9d15ae 100644
--- a/include/linux/splice.h
+++ b/include/linux/splice.h
@@ -36,6 +36,8 @@ struct splice_desc {
                 void *data;             /* cookie */
         } u;
         loff_t pos;                     /* file position */
+        size_t num_spliced;             /* number of bytes already spliced */
+        bool need_wakeup;               /* need to wake up writer */
 };
 
 struct partial_page {
@@ -66,6 +68,16 @@ extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
                                 splice_actor *);
 extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
                                   struct splice_desc *, splice_actor *);
+extern int splice_from_pipe_feed(struct pipe_inode_info *, struct splice_desc *,
+                                 splice_actor *);
+extern int splice_from_pipe_next(struct pipe_inode_info *,
+                                 struct splice_desc *);
+extern void splice_from_pipe_begin(struct splice_desc *);
+extern void splice_from_pipe_end(struct pipe_inode_info *,
+                                 struct splice_desc *);
+extern int pipe_to_file(struct pipe_inode_info *, struct pipe_buffer *,
+                        struct splice_desc *);
+
 extern ssize_t splice_to_pipe(struct pipe_inode_info *,
                               struct splice_pipe_desc *);
 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,