11 files changed, 208 insertions, 4 deletions

diff --git a/arch/i386/kernel/syscall_table.S b/arch/i386/kernel/syscall_table.S
index 4f58b9c0efe3..f48bef15b4f0 100644
--- a/arch/i386/kernel/syscall_table.S
+++ b/arch/i386/kernel/syscall_table.S
@@ -314,3 +314,4 @@ ENTRY(sys_call_table)
         .long sys_get_robust_list
         .long sys_splice
         .long sys_sync_file_range
+        .long sys_tee                   /* 315 */
diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S
index 6e16f6b35bd3..e30798811216 100644
--- a/arch/ia64/kernel/entry.S
+++ b/arch/ia64/kernel/entry.S
@@ -1609,5 +1609,6 @@ sys_call_table:
         data8 sys_set_robust_list
         data8 sys_get_robust_list
         data8 sys_sync_file_range               // 1300
+        data8 sys_tee
 
         .org sys_call_table + 8*NR_syscalls     // guard against failures to increase NR_syscalls
diff --git a/arch/powerpc/kernel/systbl.S b/arch/powerpc/kernel/systbl.S
index 1424eab450ee..a14c96403840 100644
--- a/arch/powerpc/kernel/systbl.S
+++ b/arch/powerpc/kernel/systbl.S
@@ -323,3 +323,4 @@ COMPAT_SYS(pselect6)
 COMPAT_SYS(ppoll)
 SYSCALL(unshare)
 SYSCALL(splice)
+SYSCALL(tee)
diff --git a/fs/pipe.c b/fs/pipe.c
index e984beb93a0e..7fefb10db8d9 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -131,12 +131,19 @@ static int anon_pipe_buf_steal(struct pipe_inode_info *pipe,
         return 0;
 }
 
+static void anon_pipe_buf_get(struct pipe_inode_info *info,
+                              struct pipe_buffer *buf)
+{
+        page_cache_get(buf->page);
+}
+
 static struct pipe_buf_operations anon_pipe_buf_ops = {
         .can_merge = 1,
         .map = anon_pipe_buf_map,
         .unmap = anon_pipe_buf_unmap,
         .release = anon_pipe_buf_release,
         .steal = anon_pipe_buf_steal,
+        .get = anon_pipe_buf_get,
 };
 
 static ssize_t
diff --git a/fs/splice.c b/fs/splice.c
index 5d3eda64703b..8d57e89924a6 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -125,12 +125,19 @@ static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info,
         kunmap(buf->page);
 }
 
+static void page_cache_pipe_buf_get(struct pipe_inode_info *info,
+                                    struct pipe_buffer *buf)
+{
+        page_cache_get(buf->page);
+}
+
 static struct pipe_buf_operations page_cache_pipe_buf_ops = {
         .can_merge = 0,
         .map = page_cache_pipe_buf_map,
         .unmap = page_cache_pipe_buf_unmap,
         .release = page_cache_pipe_buf_release,
         .steal = page_cache_pipe_buf_steal,
+        .get = page_cache_pipe_buf_get,
 };
 
 /*
@@ -963,3 +970,182 @@ asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
 
         return error;
 }
+
+/*
+ * Link contents of ipipe to opipe.
+ */
+static int link_pipe(struct pipe_inode_info *ipipe,
+                     struct pipe_inode_info *opipe,
+                     size_t len, unsigned int flags)
+{
+        struct pipe_buffer *ibuf, *obuf;
+        int ret = 0, do_wakeup = 0, i;
+
+        /*
+         * Potential ABBA deadlock, work around it by ordering lock
+         * grabbing by inode address. Otherwise two different processes
+         * could deadlock (one doing tee from A -> B, the other from B -> A).
+         */
+        if (ipipe->inode < opipe->inode) {
+                mutex_lock(&ipipe->inode->i_mutex);
+                mutex_lock(&opipe->inode->i_mutex);
+        } else {
+                mutex_lock(&opipe->inode->i_mutex);
+                mutex_lock(&ipipe->inode->i_mutex);
+        }
+
+        for (i = 0;; i++) {
+                if (!opipe->readers) {
+                        send_sig(SIGPIPE, current, 0);
+                        if (!ret)
+                                ret = -EPIPE;
+                        break;
+                }
+                if (ipipe->nrbufs - i) {
+                        ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
+
+                        /*
+                         * If we have room, fill this buffer
+                         */
+                        if (opipe->nrbufs < PIPE_BUFFERS) {
+                                int nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
+
+                                /*
+                                 * Get a reference to this pipe buffer,
+                                 * so we can copy the contents over.
+                                 */
+                                ibuf->ops->get(ipipe, ibuf);
+
+                                obuf = opipe->bufs + nbuf;
+                                *obuf = *ibuf;
+
+                                if (obuf->len > len)
+                                        obuf->len = len;
+
+                                opipe->nrbufs++;
+                                do_wakeup = 1;
+                                ret += obuf->len;
+                                len -= obuf->len;
+
+                                if (!len)
+                                        break;
+                                if (opipe->nrbufs < PIPE_BUFFERS)
+                                        continue;
+                        }
+
+                        /*
+                         * We have input available, but no output room.
+                         * If we already copied data, return that.
+                         */
+                        if (flags & SPLICE_F_NONBLOCK) {
+                                if (!ret)
+                                        ret = -EAGAIN;
+                                break;
+                        }
+                        if (signal_pending(current)) {
+                                if (!ret)
+                                        ret = -ERESTARTSYS;
+                                break;
+                        }
+                        if (do_wakeup) {
+                                smp_mb();
+                                if (waitqueue_active(&opipe->wait))
+                                        wake_up_interruptible(&opipe->wait);
+                                kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
+                                do_wakeup = 0;
+                        }
+
+                        opipe->waiting_writers++;
+                        pipe_wait(opipe);
+                        opipe->waiting_writers--;
+                        continue;
+                }
+
+                /*
+                 * No input buffers, do the usual checks for available
+                 * writers and blocking and wait if necessary
+                 */
+                if (!ipipe->writers)
+                        break;
+                if (!ipipe->waiting_writers) {
+                        if (ret)
+                                break;
+                }
+                if (flags & SPLICE_F_NONBLOCK) {
+                        if (!ret)
+                                ret = -EAGAIN;
+                        break;
+                }
+                if (signal_pending(current)) {
+                        if (!ret)
+                                ret = -ERESTARTSYS;
+                        break;
+                }
+
+                if (waitqueue_active(&ipipe->wait))
+                        wake_up_interruptible_sync(&ipipe->wait);
+                kill_fasync(&ipipe->fasync_writers, SIGIO, POLL_OUT);
+
+                pipe_wait(ipipe);
+        }
+
+        mutex_unlock(&ipipe->inode->i_mutex);
+        mutex_unlock(&opipe->inode->i_mutex);
+
+        if (do_wakeup) {
+                smp_mb();
+                if (waitqueue_active(&opipe->wait))
+                        wake_up_interruptible(&opipe->wait);
+                kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
+        }
+
+        return ret;
+}
+
+/*
+ * This is a tee(1) implementation that works on pipes. It doesn't copy
+ * any data, it simply references the 'in' pages on the 'out' pipe.
+ * The 'flags' used are the SPLICE_F_* variants, currently the only
+ * applicable one is SPLICE_F_NONBLOCK.
+ */
+static long do_tee(struct file *in, struct file *out, size_t len,
+                   unsigned int flags)
+{
+        struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe;
+        struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe;
+
+        /*
+         * Link ipipe to the two output pipes, consuming as we go along.
+         */
+        if (ipipe && opipe)
+                return link_pipe(ipipe, opipe, len, flags);
+
+        return -EINVAL;
+}
+
+asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags)
+{
+        struct file *in;
+        int error, fput_in;
+
+        if (unlikely(!len))
+                return 0;
+
+        error = -EBADF;
+        in = fget_light(fdin, &fput_in);
+        if (in) {
+                if (in->f_mode & FMODE_READ) {
+                        int fput_out;
+                        struct file *out = fget_light(fdout, &fput_out);
+
+                        if (out) {
+                                if (out->f_mode & FMODE_WRITE)
+                                        error = do_tee(in, out, len, flags);
+                                fput_light(out, fput_out);
+                        }
+                }
+                fput_light(in, fput_in);
+        }
+
+        return error;
+}
diff --git a/include/asm-i386/unistd.h b/include/asm-i386/unistd.h
index 6a8dd83c350f..d81d6cfc1bb4 100644
--- a/include/asm-i386/unistd.h
+++ b/include/asm-i386/unistd.h
@@ -320,8 +320,9 @@
 #define __NR_get_robust_list    312
 #define __NR_splice             313
 #define __NR_sync_file_range    314
+#define __NR_tee                315
 
-#define NR_syscalls 315
+#define NR_syscalls 316
 
 /*
  * user-visible error numbers are in the range -1 - -128: see
diff --git a/include/asm-ia64/unistd.h b/include/asm-ia64/unistd.h
index 1c749acca021..a40ebec6aeeb 100644
--- a/include/asm-ia64/unistd.h
+++ b/include/asm-ia64/unistd.h
@@ -289,12 +289,13 @@
 #define __NR_set_robust_list            1298
 #define __NR_get_robust_list            1299
 #define __NR_sync_file_range            1300
+#define __NR_tee                        1301
 
 #ifdef __KERNEL__
 
 #include <linux/config.h>
 
-#define NR_syscalls                     277 /* length of syscall table */
+#define NR_syscalls                     278 /* length of syscall table */
 
 #define __ARCH_WANT_SYS_RT_SIGACTION
 
diff --git a/include/asm-powerpc/unistd.h b/include/asm-powerpc/unistd.h
index 536ba0873052..c612f1a62772 100644
--- a/include/asm-powerpc/unistd.h
+++ b/include/asm-powerpc/unistd.h
@@ -302,8 +302,9 @@
 #define __NR_ppoll              281
 #define __NR_unshare            282
 #define __NR_splice             283
+#define __NR_tee                284
 
-#define __NR_syscalls           284
+#define __NR_syscalls           285
 
 #ifdef __KERNEL__
 #define __NR__exit __NR_exit
diff --git a/include/asm-x86_64/unistd.h b/include/asm-x86_64/unistd.h
index f21ff2c1e960..d86494e23b63 100644
--- a/include/asm-x86_64/unistd.h
+++ b/include/asm-x86_64/unistd.h
@@ -611,8 +611,10 @@ __SYSCALL(__NR_set_robust_list, sys_set_robust_list)
 __SYSCALL(__NR_get_robust_list, sys_get_robust_list)
 #define __NR_splice             275
 __SYSCALL(__NR_splice, sys_splice)
+#define __NR_tee                276
+__SYSCALL(__NR_tee, sys_tee)
 
-#define __NR_syscall_max __NR_splice
+#define __NR_syscall_max __NR_tee
 
 #ifndef __NO_STUBS
 
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 123a7c24bc72..ef7f33c0be19 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -21,6 +21,7 @@ struct pipe_buf_operations {
         void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *);
         void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
         int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
+        void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
 };
 
 struct pipe_inode_info {
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index f001bad28d9a..d3ebc0e68b2b 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -574,6 +574,8 @@ asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
                            int fd_out, loff_t __user *off_out,
                            size_t len, unsigned int flags);
 
+asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags);
+
 asmlinkage long sys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
                                         unsigned int flags);