[PATCH] Add vector AIO support

This work is initially done by Zach Brown to add support for vectored aio.
These are the core changes for AIO to support
IOCB_CMD_PREADV/IOCB_CMD_PWRITEV.

[akpm@osdl.org: huge build fix]
Signed-off-by: Zach Brown <zach.brown@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Acked-by: Benjamin LaHaise <bcrl@kvack.org>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

5 files changed, 203 insertions, 108 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 27ff56540c73..2e0d1505ee36 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -415,6 +415,7 @@ static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx)
         req->ki_retry = NULL;
         req->ki_dtor = NULL;
         req->private = NULL;
+        req->ki_iovec = NULL;
         INIT_LIST_HEAD(&req->ki_run_list);
 
         /* Check if the completion queue has enough free space to
@@ -460,6 +461,8 @@ static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
 
         if (req->ki_dtor)
                 req->ki_dtor(req);
+        if (req->ki_iovec != &req->ki_inline_vec)
+                kfree(req->ki_iovec);
         kmem_cache_free(kiocb_cachep, req);
         ctx->reqs_active--;
 
@@ -1301,69 +1304,63 @@ asmlinkage long sys_io_destroy(aio_context_t ctx)
         return -EINVAL;
 }
 
-/*
- * aio_p{read,write} are the default  ki_retry methods for
- * IO_CMD_P{READ,WRITE}.  They maintains kiocb retry state around potentially
- * multiple calls to f_op->aio_read().  They loop around partial progress
- * instead of returning -EIOCBRETRY because they don't have the means to call
- * kick_iocb().
- */
-static ssize_t aio_pread(struct kiocb *iocb)
+static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
 {
-        struct file *file = iocb->ki_filp;
-        struct address_space *mapping = file->f_mapping;
-        struct inode *inode = mapping->host;
-        ssize_t ret = 0;
-
-        do {
-                iocb->ki_inline_vec.iov_base = iocb->ki_buf;
-                iocb->ki_inline_vec.iov_len = iocb->ki_left;
-
-                ret = file->f_op->aio_read(iocb, &iocb->ki_inline_vec,
-                                                1, iocb->ki_pos);
-                /*
-                 * Can't just depend on iocb->ki_left to determine
-                 * whether we are done. This may have been a short read.
-                 */
-                if (ret > 0) {
-                        iocb->ki_buf += ret;
-                        iocb->ki_left -= ret;
+        struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg];
+
+        BUG_ON(ret <= 0);
+
+        while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) {
+                ssize_t this = min((ssize_t)iov->iov_len, ret);
+                iov->iov_base += this;
+                iov->iov_len -= this;
+                iocb->ki_left -= this;
+                ret -= this;
+                if (iov->iov_len == 0) {
+                        iocb->ki_cur_seg++;
+                        iov++;
                 }
+        }
 
-                /*
-                 * For pipes and sockets we return once we have some data; for
-                 * regular files we retry till we complete the entire read or
-                 * find that we can't read any more data (e.g short reads).
-                 */
-        } while (ret > 0 && iocb->ki_left > 0 &&
-                 !S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode));
-
-        /* This means we must have transferred all that we could */
-        /* No need to retry anymore */
-        if ((ret == 0) || (iocb->ki_left == 0))
-                ret = iocb->ki_nbytes - iocb->ki_left;
-
-        return ret;
+        /* the caller should not have done more io than what fit in
+         * the remaining iovecs */
+        BUG_ON(ret > 0 && iocb->ki_left == 0);
 }
 
-/* see aio_pread() */
-static ssize_t aio_pwrite(struct kiocb *iocb)
+static ssize_t aio_rw_vect_retry(struct kiocb *iocb)
 {
         struct file *file = iocb->ki_filp;
+        struct address_space *mapping = file->f_mapping;
+        struct inode *inode = mapping->host;
+        ssize_t (*rw_op)(struct kiocb *, const struct iovec *,
+                         unsigned long, loff_t);
         ssize_t ret = 0;
+        unsigned short opcode;
+
+        if ((iocb->ki_opcode == IOCB_CMD_PREADV) ||
+                (iocb->ki_opcode == IOCB_CMD_PREAD)) {
+                rw_op = file->f_op->aio_read;
+                opcode = IOCB_CMD_PREADV;
+        } else {
+                rw_op = file->f_op->aio_write;
+                opcode = IOCB_CMD_PWRITEV;
+        }
 
         do {
-                iocb->ki_inline_vec.iov_base = iocb->ki_buf;
-                iocb->ki_inline_vec.iov_len = iocb->ki_left;
-
-                ret = file->f_op->aio_write(iocb, &iocb->ki_inline_vec,
-                                                1, iocb->ki_pos);
-                if (ret > 0) {
-                        iocb->ki_buf += ret;
-                        iocb->ki_left -= ret;
-                }
-        } while (ret > 0 && iocb->ki_left > 0);
+                ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
+                            iocb->ki_nr_segs - iocb->ki_cur_seg,
+                            iocb->ki_pos);
+                if (ret > 0)
+                        aio_advance_iovec(iocb, ret);
+
+        /* retry all partial writes.  retry partial reads as long as its a
+         * regular file. */
+        } while (ret > 0 && iocb->ki_left > 0 &&
+                 (opcode == IOCB_CMD_PWRITEV ||
+                  (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
 
+        /* This means we must have transferred all that we could */
+        /* No need to retry anymore */
         if ((ret == 0) || (iocb->ki_left == 0))
                 ret = iocb->ki_nbytes - iocb->ki_left;
 
@@ -1390,6 +1387,38 @@ static ssize_t aio_fsync(struct kiocb *iocb)
         return ret;
 }
 
+static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb)
+{
+        ssize_t ret;
+
+        ret = rw_copy_check_uvector(type, (struct iovec __user *)kiocb->ki_buf,
+                                    kiocb->ki_nbytes, 1,
+                                    &kiocb->ki_inline_vec, &kiocb->ki_iovec);
+        if (ret < 0)
+                goto out;
+
+        kiocb->ki_nr_segs = kiocb->ki_nbytes;
+        kiocb->ki_cur_seg = 0;
+        /* ki_nbytes/left now reflect bytes instead of segs */
+        kiocb->ki_nbytes = ret;
+        kiocb->ki_left = ret;
+
+        ret = 0;
+out:
+        return ret;
+}
+
+static ssize_t aio_setup_single_vector(struct kiocb *kiocb)
+{
+        kiocb->ki_iovec = &kiocb->ki_inline_vec;
+        kiocb->ki_iovec->iov_base = kiocb->ki_buf;
+        kiocb->ki_iovec->iov_len = kiocb->ki_left;
+        kiocb->ki_nr_segs = 1;
+        kiocb->ki_cur_seg = 0;
+        kiocb->ki_nbytes = kiocb->ki_left;
+        return 0;
+}
+
 /*
  * aio_setup_iocb:
  *      Performs the initial checks and aio retry method
@@ -1412,9 +1441,12 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb)
                 ret = security_file_permission(file, MAY_READ);
                 if (unlikely(ret))
                         break;
+                ret = aio_setup_single_vector(kiocb);
+                if (ret)
+                        break;
                 ret = -EINVAL;
                 if (file->f_op->aio_read)
-                        kiocb->ki_retry = aio_pread;
+                        kiocb->ki_retry = aio_rw_vect_retry;
                 break;
         case IOCB_CMD_PWRITE:
                 ret = -EBADF;
@@ -1427,9 +1459,40 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb)
                 ret = security_file_permission(file, MAY_WRITE);
                 if (unlikely(ret))
                         break;
+                ret = aio_setup_single_vector(kiocb);
+                if (ret)
+                        break;
+                ret = -EINVAL;
+                if (file->f_op->aio_write)
+                        kiocb->ki_retry = aio_rw_vect_retry;
+                break;
+        case IOCB_CMD_PREADV:
+                ret = -EBADF;
+                if (unlikely(!(file->f_mode & FMODE_READ)))
+                        break;
+                ret = security_file_permission(file, MAY_READ);
+                if (unlikely(ret))
+                        break;
+                ret = aio_setup_vectored_rw(READ, kiocb);
+                if (ret)
+                        break;
+                ret = -EINVAL;
+                if (file->f_op->aio_read)
+                        kiocb->ki_retry = aio_rw_vect_retry;
+                break;
+        case IOCB_CMD_PWRITEV:
+                ret = -EBADF;
+                if (unlikely(!(file->f_mode & FMODE_WRITE)))
+                        break;
+                ret = security_file_permission(file, MAY_WRITE);
+                if (unlikely(ret))
+                        break;
+                ret = aio_setup_vectored_rw(WRITE, kiocb);
+                if (ret)
+                        break;
                 ret = -EINVAL;
                 if (file->f_op->aio_write)
-                        kiocb->ki_retry = aio_pwrite;
+                        kiocb->ki_retry = aio_rw_vect_retry;
                 break;
         case IOCB_CMD_FDSYNC:
                 ret = -EINVAL;
diff --git a/fs/read_write.c b/fs/read_write.c
index 4ed839bcb91c..f792000a28e6 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -511,6 +511,74 @@ ssize_t do_loop_readv_writev(struct file *filp, struct iovec *iov,
 /* A write operation does a read from user space and vice versa */
 #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
 
+ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
+                              unsigned long nr_segs, unsigned long fast_segs,
+                              struct iovec *fast_pointer,
+                              struct iovec **ret_pointer)
+  {
+        unsigned long seg;
+        ssize_t ret;
+        struct iovec *iov = fast_pointer;
+
+        /*
+         * SuS says "The readv() function *may* fail if the iovcnt argument
+         * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
+         * traditionally returned zero for zero segments, so...
+         */
+        if (nr_segs == 0) {
+                ret = 0;
+                goto out;
+        }
+
+        /*
+         * First get the "struct iovec" from user memory and
+         * verify all the pointers
+         */
+        if (nr_segs > UIO_MAXIOV) {
+                ret = -EINVAL;
+                goto out;
+        }
+        if (nr_segs > fast_segs) {
+                iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
+                if (iov == NULL) {
+                        ret = -ENOMEM;
+                        goto out;
+                }
+        }
+        if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
+                ret = -EFAULT;
+                goto out;
+        }
+
+        /*
+         * According to the Single Unix Specification we should return EINVAL
+         * if an element length is < 0 when cast to ssize_t or if the
+         * total length would overflow the ssize_t return value of the
+         * system call.
+         */
+        ret = 0;
+        for (seg = 0; seg < nr_segs; seg++) {
+                void __user *buf = iov[seg].iov_base;
+                ssize_t len = (ssize_t)iov[seg].iov_len;
+
+                /* see if we we're about to use an invalid len or if
+                 * it's about to overflow ssize_t */
+                if (len < 0 || (ret + len < ret)) {
+                        ret = -EINVAL;
+                        goto out;
+                }
+                if (unlikely(!access_ok(vrfy_dir(type), buf, len))) {
+                        ret = -EFAULT;
+                        goto out;
+                }
+
+                ret += len;
+        }
+out:
+        *ret_pointer = iov;
+        return ret;
+}
+
 static ssize_t do_readv_writev(int type, struct file *file,
                                const struct iovec __user * uvector,
                                unsigned long nr_segs, loff_t *pos)
@@ -519,64 +587,20 @@ static ssize_t do_readv_writev(int type, struct file *file,
         struct iovec iovstack[UIO_FASTIOV];
         struct iovec *iov = iovstack;
         ssize_t ret;
-        int seg;
         io_fn_t fn;
         iov_fn_t fnv;
 
-        /*
-         * SuS says "The readv() function *may* fail if the iovcnt argument
-         * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
-         * traditionally returned zero for zero segments, so...
-         */
-        ret = 0;
-        if (nr_segs == 0)
-                goto out;
-
-        /*
-         * First get the "struct iovec" from user memory and
-         * verify all the pointers
-         */
-        ret = -EINVAL;
-        if (nr_segs > UIO_MAXIOV)
-                goto out;
-        if (!file->f_op)
-                goto out;
-        if (nr_segs > UIO_FASTIOV) {
-                ret = -ENOMEM;
-                iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
-                if (!iov)
-                        goto out;
-        }
-        ret = -EFAULT;
-        if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector)))
+        if (!file->f_op) {
+                ret = -EINVAL;
                 goto out;
+        }
 
-        /*
-         * Single unix specification:
-         * We should -EINVAL if an element length is not >= 0 and fitting an
-         * ssize_t.  The total length is fitting an ssize_t
-         *
-         * Be careful here because iov_len is a size_t not an ssize_t
-         */
-        tot_len = 0;
-        ret = -EINVAL;
-        for (seg = 0; seg < nr_segs; seg++) {
-                void __user *buf = iov[seg].iov_base;
-                ssize_t len = (ssize_t)iov[seg].iov_len;
-
-                if (len < 0)    /* size_t not fitting an ssize_t .. */
-                        goto out;
-                if (unlikely(!access_ok(vrfy_dir(type), buf, len)))
-                        goto Efault;
-                tot_len += len;
-                if ((ssize_t)tot_len < 0) /* maths overflow on the ssize_t */
-                        goto out;
-        }
-        if (tot_len == 0) {
-                ret = 0;
+        ret = rw_copy_check_uvector(type, uvector, nr_segs,
+                        ARRAY_SIZE(iovstack), iovstack, &iov);
+        if (ret <= 0)
                 goto out;
-        }
 
+        tot_len = ret;
         ret = rw_verify_area(type, file, pos, tot_len);
         if (ret < 0)
                 goto out;
@@ -609,9 +633,6 @@ out:
                         fsnotify_modify(file->f_dentry);
         }
         return ret;
-Efault:
-        ret = -EFAULT;
-        goto out;
 }
 
 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
diff --git a/include/linux/aio.h b/include/linux/aio.h
index 58349e58b749..5722568fc71e 100644
--- a/include/linux/aio.h
+++ b/include/linux/aio.h
@@ -7,6 +7,7 @@
 #include <linux/uio.h>
 
 #include <asm/atomic.h>
+#include <linux/uio.h>
 
 #define AIO_MAXSEGS             4
 #define AIO_KIOGRP_NR_ATOMIC    8
@@ -114,6 +115,9 @@ struct kiocb {
         long                    ki_kicked;      /* just for testing */
         long                    ki_queued;      /* just for testing */
         struct iovec            ki_inline_vec;  /* inline vector */
+        struct iovec            *ki_iovec;
+        unsigned long           ki_nr_segs;
+        unsigned long           ki_cur_seg;
 
         struct list_head        ki_list;        /* the aio core uses this
                                                  * for cancellation */
diff --git a/include/linux/aio_abi.h b/include/linux/aio_abi.h
index 30fdcc89d142..3466b1d0ffd2 100644
--- a/include/linux/aio_abi.h
+++ b/include/linux/aio_abi.h
@@ -41,6 +41,8 @@ enum {
          * IOCB_CMD_POLL = 5,
          */
         IOCB_CMD_NOOP = 6,
+        IOCB_CMD_PREADV = 7,
+        IOCB_CMD_PWRITEV = 8,
 };
 
 /* read() from /dev/aio returns these structures. */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 011129f8803e..4bb70871873f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1150,6 +1150,11 @@ struct inode_operations {
 
 struct seq_file;
 
+ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
+                                unsigned long nr_segs, unsigned long fast_segs,
+                                struct iovec *fast_pointer,
+                                struct iovec **ret_pointer);
+
 extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *);
 extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *);
 extern ssize_t vfs_readv(struct file *, const struct iovec __user *,