new methods: ->read_iter() and ->write_iter()

Beginning to introduce those.  Just the callers for now, and it's
clumsier than it'll eventually become; once we finish converting
aio_read and aio_write instances, the things will get nicer.

For now, these guys are in parallel to ->aio_read() and ->aio_write();
they take iocb and iov_iter, with everything in iov_iter already
validated.  File offset is passed in iocb->ki_pos, iov/nr_segs -
in iov_iter.

Main concerns in that series are stack footprint and ability to
split the damn thing cleanly.

[fix from Peter Ujfalusi <peter.ujfalusi@ti.com> folded]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 9b0d5a3..b18dd17 100644 (file)
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -430,6 +430,8 @@ prototypes:
        ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
        ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
        ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
+       ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);
+       ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
        int (*iterate) (struct file *, struct dir_context *);
        unsigned int (*poll) (struct file *, struct poll_table_struct *);
        long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);

diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 1846374..a1d0d7a 100644 (file)
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -806,6 +806,8 @@ struct file_operations {
        ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
        ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
        ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
+       ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);
+       ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
        int (*iterate) (struct file *, struct dir_context *);
        unsigned int (*poll) (struct file *, struct poll_table_struct *);
        long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
@@ -836,11 +838,15 @@ otherwise noted.
 
   read: called by read(2) and related system calls
 
-  aio_read: called by io_submit(2) and other asynchronous I/O operations
+  aio_read: vectored, possibly asynchronous read
+
+  read_iter: possibly asynchronous read with iov_iter as destination
 
   write: called by write(2) and related system calls
 
-  aio_write: called by io_submit(2) and other asynchronous I/O operations
+  aio_write: vectored, possibly asynchronous write
+
+  write_iter: possibly asynchronous write with iov_iter as source
 
   iterate: called when the VFS needs to read the directory contents
 

diff --git a/fs/aio.c b/fs/aio.c
index a0ed6c7..56b2860 100644 (file)
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1241,6 +1241,7 @@ SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
 
 typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *,
                            unsigned long, loff_t);
+typedef ssize_t (rw_iter_op)(struct kiocb *, struct iov_iter *);
 
 static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
                                     int rw, char __user *buf,
@@ -1298,7 +1299,9 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
        int rw;
        fmode_t mode;
        aio_rw_op *rw_op;
+       rw_iter_op *iter_op;
        struct iovec inline_vec, *iovec = &inline_vec;
+       struct iov_iter iter;
 
        switch (opcode) {
        case IOCB_CMD_PREAD:
@@ -1306,6 +1309,7 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
                mode    = FMODE_READ;
                rw      = READ;
                rw_op   = file->f_op->aio_read;
+               iter_op = file->f_op->read_iter;
                goto rw_common;
 
        case IOCB_CMD_PWRITE:
@@ -1313,12 +1317,13 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
                mode    = FMODE_WRITE;
                rw      = WRITE;
                rw_op   = file->f_op->aio_write;
+               iter_op = file->f_op->write_iter;
                goto rw_common;
 rw_common:
                if (unlikely(!(file->f_mode & mode)))
                        return -EBADF;
 
-               if (!rw_op)
+               if (!rw_op && !iter_op)
                        return -EINVAL;
 
                ret = (opcode == IOCB_CMD_PREADV ||
@@ -1347,7 +1352,12 @@ rw_common:
                if (rw == WRITE)
                        file_start_write(file);
 
-               ret = rw_op(req, iovec, nr_segs, req->ki_pos);
+               if (iter_op) {
+                       iov_iter_init(&iter, rw, iovec, nr_segs, req->ki_nbytes);
+                       ret = iter_op(req, &iter);
+               } else {
+                       ret = rw_op(req, iovec, nr_segs, req->ki_pos);
+               }
 
                if (rw == WRITE)
                        file_end_write(file);

diff --git a/fs/file_table.c b/fs/file_table.c
index be73cbc..f8cc881 100644 (file)
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -175,9 +175,11 @@ struct file *alloc_file(struct path *path, fmode_t mode,
        file->f_path = *path;
        file->f_inode = path->dentry->d_inode;
        file->f_mapping = path->dentry->d_inode->i_mapping;
-       if ((mode & FMODE_READ) && likely(fop->read || fop->aio_read))
+       if ((mode & FMODE_READ) &&
+            likely(fop->read || fop->aio_read || fop->read_iter))
                mode |= FMODE_CAN_READ;
-       if ((mode & FMODE_WRITE) && likely(fop->write || fop->aio_write))
+       if ((mode & FMODE_WRITE) &&
+            likely(fop->write || fop->aio_write || fop->write_iter))
                mode |= FMODE_CAN_WRITE;
        file->f_mode = mode;
        file->f_op = fop;

diff --git a/fs/open.c b/fs/open.c
index 39d3d04..36662d0 100644 (file)
--- a/fs/open.c
+++ b/fs/open.c
@@ -725,9 +725,11 @@ static int do_dentry_open(struct file *f,
        }
        if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
                i_readcount_inc(inode);
-       if ((f->f_mode & FMODE_READ) && likely(f->f_op->read || f->f_op->aio_read))
+       if ((f->f_mode & FMODE_READ) &&
+            likely(f->f_op->read || f->f_op->aio_read || f->f_op->read_iter))
                f->f_mode |= FMODE_CAN_READ;
-       if ((f->f_mode & FMODE_WRITE) && likely(f->f_op->write || f->f_op->aio_write))
+       if ((f->f_mode & FMODE_WRITE) &&
+            likely(f->f_op->write || f->f_op->aio_write || f->f_op->write_iter))
                f->f_mode |= FMODE_CAN_WRITE;
 
        f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);

diff --git a/fs/read_write.c b/fs/read_write.c
index d29d2a3..fe2f9d5 100644 (file)
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -25,6 +25,7 @@
 typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
 typedef ssize_t (*iov_fn_t)(struct kiocb *, const struct iovec *,
                unsigned long, loff_t);
+typedef ssize_t (*iter_fn_t)(struct kiocb *, struct iov_iter *);
 
 const struct file_operations generic_ro_fops = {
        .llseek         = generic_file_llseek,
@@ -390,6 +391,27 @@ ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *pp
 
 EXPORT_SYMBOL(do_sync_read);
 
+ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
+{
+       struct iovec iov = { .iov_base = buf, .iov_len = len };
+       struct kiocb kiocb;
+       struct iov_iter iter;
+       ssize_t ret;
+
+       init_sync_kiocb(&kiocb, filp);
+       kiocb.ki_pos = *ppos;
+       kiocb.ki_nbytes = len;
+       iov_iter_init(&iter, READ, &iov, 1, len);
+
+       ret = filp->f_op->read_iter(&kiocb, &iter);
+       if (-EIOCBQUEUED == ret)
+               ret = wait_on_sync_kiocb(&kiocb);
+       *ppos = kiocb.ki_pos;
+       return ret;
+}
+
+EXPORT_SYMBOL(new_sync_read);
+
 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
 {
        ssize_t ret;
@@ -406,8 +428,10 @@ ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
                count = ret;
                if (file->f_op->read)
                        ret = file->f_op->read(file, buf, count, pos);
-               else
+               else if (file->f_op->aio_read)
                        ret = do_sync_read(file, buf, count, pos);
+               else
+                       ret = new_sync_read(file, buf, count, pos);
                if (ret > 0) {
                        fsnotify_access(file);
                        add_rchar(current, ret);
@@ -439,6 +463,27 @@ ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, lof
 
 EXPORT_SYMBOL(do_sync_write);
 
+ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
+{
+       struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len };
+       struct kiocb kiocb;
+       struct iov_iter iter;
+       ssize_t ret;
+
+       init_sync_kiocb(&kiocb, filp);
+       kiocb.ki_pos = *ppos;
+       kiocb.ki_nbytes = len;
+       iov_iter_init(&iter, WRITE, &iov, 1, len);
+
+       ret = filp->f_op->write_iter(&kiocb, &iter);
+       if (-EIOCBQUEUED == ret)
+               ret = wait_on_sync_kiocb(&kiocb);
+       *ppos = kiocb.ki_pos;
+       return ret;
+}
+
+EXPORT_SYMBOL(new_sync_write);
+
 ssize_t __kernel_write(struct file *file, const char *buf, size_t count, loff_t *pos)
 {
        mm_segment_t old_fs;
@@ -455,8 +500,10 @@ ssize_t __kernel_write(struct file *file, const char *buf, size_t count, loff_t
                count =  MAX_RW_COUNT;
        if (file->f_op->write)
                ret = file->f_op->write(file, p, count, pos);
-       else
+       else if (file->f_op->aio_write)
                ret = do_sync_write(file, p, count, pos);
+       else
+               ret = new_sync_write(file, p, count, pos);
        set_fs(old_fs);
        if (ret > 0) {
                fsnotify_modify(file);
@@ -483,8 +530,10 @@ ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_
                file_start_write(file);
                if (file->f_op->write)
                        ret = file->f_op->write(file, buf, count, pos);
-               else
+               else if (file->f_op->aio_write)
                        ret = do_sync_write(file, buf, count, pos);
+               else
+                       ret = new_sync_write(file, buf, count, pos);
                if (ret > 0) {
                        fsnotify_modify(file);
                        add_wchar(current, ret);
@@ -601,6 +650,25 @@ unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
 }
 EXPORT_SYMBOL(iov_shorten);
 
+static ssize_t do_iter_readv_writev(struct file *filp, int rw, const struct iovec *iov,
+               unsigned long nr_segs, size_t len, loff_t *ppos, iter_fn_t fn)
+{
+       struct kiocb kiocb;
+       struct iov_iter iter;
+       ssize_t ret;
+
+       init_sync_kiocb(&kiocb, filp);
+       kiocb.ki_pos = *ppos;
+       kiocb.ki_nbytes = len;
+
+       iov_iter_init(&iter, rw, iov, nr_segs, len);
+       ret = fn(&kiocb, &iter);
+       if (ret == -EIOCBQUEUED)
+               ret = wait_on_sync_kiocb(&kiocb);
+       *ppos = kiocb.ki_pos;
+       return ret;
+}
+
 static ssize_t do_sync_readv_writev(struct file *filp, const struct iovec *iov,
                unsigned long nr_segs, size_t len, loff_t *ppos, iov_fn_t fn)
 {
@@ -738,6 +806,7 @@ static ssize_t do_readv_writev(int type, struct file *file,
        ssize_t ret;
        io_fn_t fn;
        iov_fn_t fnv;
+       iter_fn_t iter_fn;
 
        ret = rw_copy_check_uvector(type, uvector, nr_segs,
                                    ARRAY_SIZE(iovstack), iovstack, &iov);
@@ -753,13 +822,18 @@ static ssize_t do_readv_writev(int type, struct file *file,
        if (type == READ) {
                fn = file->f_op->read;
                fnv = file->f_op->aio_read;
+               iter_fn = file->f_op->read_iter;
        } else {
                fn = (io_fn_t)file->f_op->write;
                fnv = file->f_op->aio_write;
+               iter_fn = file->f_op->write_iter;
                file_start_write(file);
        }
 
-       if (fnv)
+       if (iter_fn)
+               ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len,
+                                               pos, iter_fn);
+       else if (fnv)
                ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
                                                pos, fnv);
        else
@@ -912,6 +986,7 @@ static ssize_t compat_do_readv_writev(int type, struct file *file,
        ssize_t ret;
        io_fn_t fn;
        iov_fn_t fnv;
+       iter_fn_t iter_fn;
 
        ret = compat_rw_copy_check_uvector(type, uvector, nr_segs,
                                               UIO_FASTIOV, iovstack, &iov);
@@ -927,13 +1002,18 @@ static ssize_t compat_do_readv_writev(int type, struct file *file,
        if (type == READ) {
                fn = file->f_op->read;
                fnv = file->f_op->aio_read;
+               iter_fn = file->f_op->read_iter;
        } else {
                fn = (io_fn_t)file->f_op->write;
                fnv = file->f_op->aio_write;
+               iter_fn = file->f_op->write_iter;
                file_start_write(file);
        }
 
-       if (fnv)
+       if (iter_fn)
+               ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len,
+                                               pos, iter_fn);
+       else if (fnv)
                ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
                                                pos, fnv);
        else

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 75eb713..17535e0 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1451,6 +1451,8 @@ struct block_device_operations;
 #define HAVE_COMPAT_IOCTL 1
 #define HAVE_UNLOCKED_IOCTL 1
 
+struct iov_iter;
+
 struct file_operations {
        struct module *owner;
        loff_t (*llseek) (struct file *, loff_t, int);
@@ -1458,6 +1460,8 @@ struct file_operations {
        ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
        ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
        ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
+       ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);
+       ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
        int (*iterate) (struct file *, struct dir_context *);
        unsigned int (*poll) (struct file *, struct poll_table_struct *);
        long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
@@ -2415,6 +2419,8 @@ extern ssize_t generic_file_direct_write(struct kiocb *, struct iov_iter *, loff
 extern ssize_t generic_perform_write(struct file *, struct iov_iter *, loff_t);
 extern ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
 extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
+extern ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
+extern ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
 
 /* fs/block_dev.c */
 extern ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,