[PATCH] splice: pass offset around for ->splice_read() and ->splice_write()

We need not use ->f_pos as the offset for the file input/output. If the
user passed an offset pointer in through sys_splice(), just use that and
leave ->f_pos alone.

Signed-off-by: Jens Axboe <axboe@suse.de>

5 files changed, 68 insertions, 60 deletions

diff --git a/fs/splice.c b/fs/splice.c
index e50a460239dd..5d3eda64703b 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -231,8 +231,9 @@ static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages,
 }
 
 static int
-__generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
-                           size_t len, unsigned int flags)
+__generic_file_splice_read(struct file *in, loff_t *ppos,
+                           struct pipe_inode_info *pipe, size_t len,
+                           unsigned int flags)
 {
         struct address_space *mapping = in->f_mapping;
         unsigned int offset, nr_pages;
@@ -241,8 +242,8 @@ __generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
         pgoff_t index;
         int i, error;
 
-        index = in->f_pos >> PAGE_CACHE_SHIFT;
-        offset = in->f_pos & ~PAGE_CACHE_MASK;
+        index = *ppos >> PAGE_CACHE_SHIFT;
+        offset = *ppos & ~PAGE_CACHE_MASK;
         nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 
         if (nr_pages > PIPE_BUFFERS)
@@ -348,8 +349,9 @@ fill_it:
  *
  * Will read pages from given file and fill them into a pipe.
  */
-ssize_t generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
-                                 size_t len, unsigned int flags)
+ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
+                                 struct pipe_inode_info *pipe, size_t len,
+                                 unsigned int flags)
 {
         ssize_t spliced;
         int ret;
@@ -358,12 +360,12 @@ ssize_t generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
         spliced = 0;
 
         while (len) {
-                ret = __generic_file_splice_read(in, pipe, len, flags);
+                ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
 
                 if (ret <= 0)
                         break;
 
-                in->f_pos += ret;
+                *ppos += ret;
                 len -= ret;
                 spliced += ret;
 
@@ -561,7 +563,7 @@ typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
  * to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
  */
 static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
-                              size_t len, unsigned int flags,
+                              loff_t *ppos, size_t len, unsigned int flags,
                               splice_actor *actor)
 {
         int ret, do_wakeup, err;
@@ -573,7 +575,7 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
         sd.total_len = len;
         sd.flags = flags;
         sd.file = out;
-        sd.pos = out->f_pos;
+        sd.pos = *ppos;
 
         if (pipe->inode)
                 mutex_lock(&pipe->inode->i_mutex);
@@ -656,9 +658,7 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
                 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
         }
 
-        out->f_pos = sd.pos;
         return ret;
-
 }
 
 /**
@@ -674,12 +674,12 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
  */
 ssize_t
 generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
-                          size_t len, unsigned int flags)
+                          loff_t *ppos, size_t len, unsigned int flags)
 {
         struct address_space *mapping = out->f_mapping;
         ssize_t ret;
 
-        ret = move_from_pipe(pipe, out, len, flags, pipe_to_file);
+        ret = move_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
 
         /*
          * If file or inode is SYNC and we actually wrote some data, sync it.
@@ -715,9 +715,9 @@ EXPORT_SYMBOL(generic_file_splice_write);
  *
  */
 ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
-                                size_t len, unsigned int flags)
+                                loff_t *ppos, size_t len, unsigned int flags)
 {
-        return move_from_pipe(pipe, out, len, flags, pipe_to_sendpage);
+        return move_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
 }
 
 EXPORT_SYMBOL(generic_splice_sendpage);
@@ -726,9 +726,8 @@ EXPORT_SYMBOL(generic_splice_sendpage);
  * Attempt to initiate a splice from pipe to file.
  */
 static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
-                           size_t len, unsigned int flags)
+                           loff_t *ppos, size_t len, unsigned int flags)
 {
-        loff_t pos;
         int ret;
 
         if (unlikely(!out->f_op || !out->f_op->splice_write))
@@ -737,22 +736,21 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
         if (unlikely(!(out->f_mode & FMODE_WRITE)))
                 return -EBADF;
 
-        pos = out->f_pos;
-
-        ret = rw_verify_area(WRITE, out, &pos, len);
+        ret = rw_verify_area(WRITE, out, ppos, len);
         if (unlikely(ret < 0))
                 return ret;
 
-        return out->f_op->splice_write(pipe, out, len, flags);
+        return out->f_op->splice_write(pipe, out, ppos, len, flags);
 }
 
 /*
  * Attempt to initiate a splice from a file to a pipe.
  */
-static long do_splice_to(struct file *in, struct pipe_inode_info *pipe,
-                         size_t len, unsigned int flags)
+static long do_splice_to(struct file *in, loff_t *ppos,
+                         struct pipe_inode_info *pipe, size_t len,
+                         unsigned int flags)
 {
-        loff_t pos, isize, left;
+        loff_t isize, left;
         int ret;
 
         if (unlikely(!in->f_op || !in->f_op->splice_read))
@@ -761,28 +759,27 @@ static long do_splice_to(struct file *in, struct pipe_inode_info *pipe,
         if (unlikely(!(in->f_mode & FMODE_READ)))
                 return -EBADF;
 
-        pos = in->f_pos;
-
-        ret = rw_verify_area(READ, in, &pos, len);
+        ret = rw_verify_area(READ, in, ppos, len);
         if (unlikely(ret < 0))
                 return ret;
 
         isize = i_size_read(in->f_mapping->host);
-        if (unlikely(in->f_pos >= isize))
+        if (unlikely(*ppos >= isize))
                 return 0;
         
-        left = isize - in->f_pos;
+        left = isize - *ppos;
         if (unlikely(left < len))
                 len = left;
 
-        return in->f_op->splice_read(in, pipe, len, flags);
+        return in->f_op->splice_read(in, ppos, pipe, len, flags);
 }
 
-long do_splice_direct(struct file *in, struct file *out, size_t len,
-                      unsigned int flags)
+long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
+                      size_t len, unsigned int flags)
 {
         struct pipe_inode_info *pipe;
         long ret, bytes;
+        loff_t out_off;
         umode_t i_mode;
         int i;
 
@@ -820,6 +817,7 @@ long do_splice_direct(struct file *in, struct file *out, size_t len,
          */
         ret = 0;
         bytes = 0;
+        out_off = 0;
 
         while (len) {
                 size_t read_len, max_read_len;
@@ -829,7 +827,7 @@ long do_splice_direct(struct file *in, struct file *out, size_t len,
                  */
                 max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));
 
-                ret = do_splice_to(in, pipe, max_read_len, flags);
+                ret = do_splice_to(in, ppos, pipe, max_read_len, flags);
                 if (unlikely(ret < 0))
                         goto out_release;
 
@@ -840,7 +838,7 @@ long do_splice_direct(struct file *in, struct file *out, size_t len,
                  * must not do the output in nonblocking mode as then we
                  * could get stuck data in the internal pipe:
                  */
-                ret = do_splice_from(pipe, out, read_len,
+                ret = do_splice_from(pipe, out, &out_off, read_len,
                                      flags & ~SPLICE_F_NONBLOCK);
                 if (unlikely(ret < 0))
                         goto out_release;
@@ -898,6 +896,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
                       size_t len, unsigned int flags)
 {
         struct pipe_inode_info *pipe;
+        loff_t offset, *off;
 
         pipe = in->f_dentry->d_inode->i_pipe;
         if (pipe) {
@@ -906,12 +905,13 @@ static long do_splice(struct file *in, loff_t __user *off_in,
                 if (off_out) {
                         if (out->f_op->llseek == no_llseek)
                                 return -EINVAL;
-                        if (copy_from_user(&out->f_pos, off_out,
-                                           sizeof(loff_t)))
+                        if (copy_from_user(&offset, off_out, sizeof(loff_t)))
                                 return -EFAULT;
-                }
+                        off = &offset;
+                } else
+                        off = &out->f_pos;
 
-                return do_splice_from(pipe, out, len, flags);
+                return do_splice_from(pipe, out, off, len, flags);
         }
 
         pipe = out->f_dentry->d_inode->i_pipe;
@@ -921,11 +921,13 @@ static long do_splice(struct file *in, loff_t __user *off_in,
                 if (off_in) {
                         if (in->f_op->llseek == no_llseek)
                                 return -EINVAL;
-                        if (copy_from_user(&in->f_pos, off_in, sizeof(loff_t)))
+                        if (copy_from_user(&offset, off_in, sizeof(loff_t)))
                                 return -EFAULT;
-                }
+                        off = &offset;
+                } else
+                        off = &in->f_pos;
 
-                return do_splice_to(in, pipe, len, flags);
+                return do_splice_to(in, off, pipe, len, flags);
         }
 
         return -EINVAL;
diff --git a/fs/xfs/linux-2.6/xfs_file.c b/fs/xfs/linux-2.6/xfs_file.c
index 269721af02f3..c847416f6d10 100644
--- a/fs/xfs/linux-2.6/xfs_file.c
+++ b/fs/xfs/linux-2.6/xfs_file.c
@@ -252,6 +252,7 @@ xfs_file_sendfile_invis(
 STATIC ssize_t
 xfs_file_splice_read(
         struct file             *infilp,
+        loff_t                  *ppos,
         struct pipe_inode_info  *pipe,
         size_t                  len,
         unsigned int            flags)
@@ -259,13 +260,14 @@ xfs_file_splice_read(
         vnode_t                 *vp = vn_from_inode(infilp->f_dentry->d_inode);
         ssize_t                 rval;
 
-        VOP_SPLICE_READ(vp, infilp, pipe, len, flags, 0, NULL, rval);
+        VOP_SPLICE_READ(vp, infilp, ppos, pipe, len, flags, 0, NULL, rval);
         return rval;
 }
 
 STATIC ssize_t
 xfs_file_splice_read_invis(
         struct file             *infilp,
+        loff_t                  *ppos,
         struct pipe_inode_info  *pipe,
         size_t                  len,
         unsigned int            flags)
@@ -273,7 +275,7 @@ xfs_file_splice_read_invis(
         vnode_t                 *vp = vn_from_inode(infilp->f_dentry->d_inode);
         ssize_t                 rval;
 
-        VOP_SPLICE_READ(vp, infilp, pipe, len, flags, IO_INVIS, NULL, rval);
+        VOP_SPLICE_READ(vp, infilp, ppos, pipe, len, flags, IO_INVIS, NULL, rval);
         return rval;
 }
 
@@ -281,13 +283,14 @@ STATIC ssize_t
 xfs_file_splice_write(
         struct pipe_inode_info  *pipe,
         struct file             *outfilp,
+        loff_t                  *ppos,
         size_t                  len,
         unsigned int            flags)
 {
         vnode_t                 *vp = vn_from_inode(outfilp->f_dentry->d_inode);
         ssize_t                 rval;
 
-        VOP_SPLICE_WRITE(vp, pipe, outfilp, len, flags, 0, NULL, rval);
+        VOP_SPLICE_WRITE(vp, pipe, outfilp, ppos, len, flags, 0, NULL, rval);
         return rval;
 }
 
@@ -295,13 +298,14 @@ STATIC ssize_t
 xfs_file_splice_write_invis(
         struct pipe_inode_info  *pipe,
         struct file             *outfilp,
+        loff_t                  *ppos,
         size_t                  len,
         unsigned int            flags)
 {
         vnode_t                 *vp = vn_from_inode(outfilp->f_dentry->d_inode);
         ssize_t                 rval;
 
-        VOP_SPLICE_WRITE(vp, pipe, outfilp, len, flags, IO_INVIS, NULL, rval);
+        VOP_SPLICE_WRITE(vp, pipe, outfilp, ppos, len, flags, IO_INVIS, NULL, rval);
         return rval;
 }
 
diff --git a/fs/xfs/linux-2.6/xfs_lrw.c b/fs/xfs/linux-2.6/xfs_lrw.c
index 74a52937f208..67efe3308980 100644
--- a/fs/xfs/linux-2.6/xfs_lrw.c
+++ b/fs/xfs/linux-2.6/xfs_lrw.c
@@ -338,6 +338,7 @@ ssize_t
 xfs_splice_read(
         bhv_desc_t              *bdp,
         struct file             *infilp,
+        loff_t                  *ppos,
         struct pipe_inode_info  *pipe,
         size_t                  count,
         int                     flags,
@@ -360,7 +361,7 @@ xfs_splice_read(
                 int error;
 
                 error = XFS_SEND_DATA(mp, DM_EVENT_READ, BHV_TO_VNODE(bdp),
-                                        infilp->f_pos, count,
+                                        *ppos, count,
                                         FILP_DELAY_FLAG(infilp), &locktype);
                 if (error) {
                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
@@ -368,8 +369,8 @@ xfs_splice_read(
                 }
         }
         xfs_rw_enter_trace(XFS_SPLICE_READ_ENTER, &ip->i_iocore,
-                           pipe, count, infilp->f_pos, ioflags);
-        ret = generic_file_splice_read(infilp, pipe, count, flags);
+                           pipe, count, *ppos, ioflags);
+        ret = generic_file_splice_read(infilp, ppos, pipe, count, flags);
         if (ret > 0)
                 XFS_STATS_ADD(xs_read_bytes, ret);
 
@@ -382,6 +383,7 @@ xfs_splice_write(
         bhv_desc_t              *bdp,
         struct pipe_inode_info  *pipe,
         struct file             *outfilp,
+        loff_t                  *ppos,
         size_t                  count,
         int                     flags,
         int                     ioflags,
@@ -403,7 +405,7 @@ xfs_splice_write(
                 int error;
 
                 error = XFS_SEND_DATA(mp, DM_EVENT_WRITE, BHV_TO_VNODE(bdp),
-                                        outfilp->f_pos, count,
+                                        *ppos, count,
                                         FILP_DELAY_FLAG(outfilp), &locktype);
                 if (error) {
                         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
@@ -411,8 +413,8 @@ xfs_splice_write(
                 }
         }
         xfs_rw_enter_trace(XFS_SPLICE_WRITE_ENTER, &ip->i_iocore,
-                           pipe, count, outfilp->f_pos, ioflags);
-        ret = generic_file_splice_write(pipe, outfilp, count, flags);
+                           pipe, count, *ppos, ioflags);
+        ret = generic_file_splice_write(pipe, outfilp, ppos, count, flags);
         if (ret > 0)
                 XFS_STATS_ADD(xs_write_bytes, ret);
 
diff --git a/fs/xfs/linux-2.6/xfs_lrw.h b/fs/xfs/linux-2.6/xfs_lrw.h
index 55c689a86ad2..8f4539952350 100644
--- a/fs/xfs/linux-2.6/xfs_lrw.h
+++ b/fs/xfs/linux-2.6/xfs_lrw.h
@@ -93,11 +93,11 @@ extern ssize_t xfs_write(struct bhv_desc *, struct kiocb *,
 extern ssize_t xfs_sendfile(struct bhv_desc *, struct file *,
                                 loff_t *, int, size_t, read_actor_t,
                                 void *, struct cred *);
-extern ssize_t xfs_splice_read(struct bhv_desc *, struct file *,
+extern ssize_t xfs_splice_read(struct bhv_desc *, struct file *, loff_t *,
                                 struct pipe_inode_info *, size_t, int, int,
                                 struct cred *);
 extern ssize_t xfs_splice_write(struct bhv_desc *, struct pipe_inode_info *,
-                                struct file *, size_t, int, int,
+                                struct file *, loff_t *, size_t, int, int,
                                 struct cred *);
 
 #endif  /* __XFS_LRW_H__ */
diff --git a/fs/xfs/linux-2.6/xfs_vnode.h b/fs/xfs/linux-2.6/xfs_vnode.h
index 88b09f186289..2a8e16c22353 100644
--- a/fs/xfs/linux-2.6/xfs_vnode.h
+++ b/fs/xfs/linux-2.6/xfs_vnode.h
@@ -173,11 +173,11 @@ typedef ssize_t (*vop_write_t)(bhv_desc_t *, struct kiocb *,
 typedef ssize_t (*vop_sendfile_t)(bhv_desc_t *, struct file *,
                                 loff_t *, int, size_t, read_actor_t,
                                 void *, struct cred *);
-typedef ssize_t (*vop_splice_read_t)(bhv_desc_t *, struct file *,
+typedef ssize_t (*vop_splice_read_t)(bhv_desc_t *, struct file *, loff_t *,
                                 struct pipe_inode_info *, size_t, int, int,
                                 struct cred *);
 typedef ssize_t (*vop_splice_write_t)(bhv_desc_t *, struct pipe_inode_info *,
-                                struct file *, size_t, int, int,
+                                struct file *, loff_t *, size_t, int, int,
                                 struct cred *);
 typedef int     (*vop_ioctl_t)(bhv_desc_t *, struct inode *, struct file *,
                                 int, unsigned int, void __user *);
@@ -284,10 +284,10 @@ typedef struct vnodeops {
         rv = _VOP_(vop_write, vp)((vp)->v_fbhv,file,iov,segs,offset,ioflags,cr)
 #define VOP_SENDFILE(vp,f,off,ioflags,cnt,act,targ,cr,rv)               \
         rv = _VOP_(vop_sendfile, vp)((vp)->v_fbhv,f,off,ioflags,cnt,act,targ,cr)
-#define VOP_SPLICE_READ(vp,f,pipe,cnt,fl,iofl,cr,rv)                    \
-        rv = _VOP_(vop_splice_read, vp)((vp)->v_fbhv,f,pipe,cnt,fl,iofl,cr)
-#define VOP_SPLICE_WRITE(vp,f,pipe,cnt,fl,iofl,cr,rv)                   \
-        rv = _VOP_(vop_splice_write, vp)((vp)->v_fbhv,f,pipe,cnt,fl,iofl,cr)
+#define VOP_SPLICE_READ(vp,f,o,pipe,cnt,fl,iofl,cr,rv)                  \
+        rv = _VOP_(vop_splice_read, vp)((vp)->v_fbhv,f,o,pipe,cnt,fl,iofl,cr)
+#define VOP_SPLICE_WRITE(vp,f,o,pipe,cnt,fl,iofl,cr,rv)                 \
+        rv = _VOP_(vop_splice_write, vp)((vp)->v_fbhv,f,o,pipe,cnt,fl,iofl,cr)
 #define VOP_BMAP(vp,of,sz,rw,b,n,rv)                                    \
         rv = _VOP_(vop_bmap, vp)((vp)->v_fbhv,of,sz,rw,b,n)
 #define VOP_OPEN(vp, cr, rv)                                            \