[PATCH v5 0/6] Add preadv & pwritev system calls.

[PATCH v5 0/6] Add preadv & pwritev system calls.

[y]

From: Gerd Hoffmann <kraxel@redhat.com>

  Hi folks,

Next round of the preadv & pwritev patch series, addressing review
comments:

 * Common code for the compat syscall versions is factored
   out in preparing patches.  
 * Added prototypes to syscall.h
 * Fixup some whitespace damage.

It's also the last release before I fall off the internet for the x-mas
and new-year holidays.  I'll be online again starting Jan 5th and will
deal with the remaining issues (if any) then.

cheers,
  Gerd

[Patch v5 1/6] Add missing accounting calls to compat_sys_{readv,writev}.

[y]

From: Gerd Hoffmann <kraxel@redhat.com>

[ Note: unrelated bugfix spotted during preadv review,
  included for completeness, akpm picked it into -mm already. ]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 fs/compat.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/fs/compat.c b/fs/compat.c
index e5f49f5..aab2234 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1187,6 +1187,9 @@ compat_sys_readv(unsigned long fd, const struct compat_iovec __user *vec, unsign
 	ret = compat_do_readv_writev(READ, file, vec, vlen, &file->f_pos);
 
 out:
+	if (ret > 0)
+		add_rchar(current, ret);
+	inc_syscr(current);
 	fput(file);
 	return ret;
 }
@@ -1210,6 +1213,9 @@ compat_sys_writev(unsigned long fd, const struct compat_iovec __user *vec, unsig
 	ret = compat_do_readv_writev(WRITE, file, vec, vlen, &file->f_pos);
 
 out:
+	if (ret > 0)
+		add_wchar(current, ret);
+	inc_syscw(current);
 	fput(file);
 	return ret;
 }
-- 
1.5.6.5

[Patch v5 2/6] create compat_readv()

[y]

From: Gerd Hoffmann <kraxel@redhat.com>

Factor out some code from compat_sys_readv() which can be shared with the
upcoming compat_sys_preadv().

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 fs/compat.c |   24 ++++++++++++++++--------
 1 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/fs/compat.c b/fs/compat.c
index aab2234..361cb7d 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1167,16 +1167,11 @@ out:
 	return ret;
 }
 
-asmlinkage ssize_t
-compat_sys_readv(unsigned long fd, const struct compat_iovec __user *vec, unsigned long vlen)
+static size_t compat_readv(struct file *file, const struct compat_iovec __user *vec,
+                           unsigned long vlen, loff_t *pos)
 {
-	struct file *file;
 	ssize_t ret = -EBADF;
 
-	file = fget(fd);
-	if (!file)
-		return -EBADF;
-
 	if (!(file->f_mode & FMODE_READ))
 		goto out;
 
@@ -1184,12 +1179,25 @@ compat_sys_readv(unsigned long fd, const struct compat_iovec __user *vec, unsign
 	if (!file->f_op || (!file->f_op->aio_read && !file->f_op->read))
 		goto out;
 
-	ret = compat_do_readv_writev(READ, file, vec, vlen, &file->f_pos);
+	ret = compat_do_readv_writev(READ, file, vec, vlen, pos);
 
 out:
 	if (ret > 0)
 		add_rchar(current, ret);
 	inc_syscr(current);
+	return ret;
+}
+
+asmlinkage ssize_t
+compat_sys_readv(unsigned long fd, const struct compat_iovec __user *vec, unsigned long vlen)
+{
+	struct file *file;
+	ssize_t ret;
+
+	file = fget(fd);
+	if (!file)
+		return -EBADF;
+	ret = compat_readv(file, vec, vlen, &file->f_pos);
 	fput(file);
 	return ret;
 }
-- 
1.5.6.5

[Patch v5 3/6] create compat_writev()

[y]

From: Gerd Hoffmann <kraxel@redhat.com>

Factor out some code from compat_sys_writev() which can be shared with the
upcoming compat_sys_pwritev().

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 fs/compat.c |   25 +++++++++++++++++--------
 1 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/fs/compat.c b/fs/compat.c
index 361cb7d..1ca314f 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1202,15 +1202,11 @@ compat_sys_readv(unsigned long fd, const struct compat_iovec __user *vec, unsign
 	return ret;
 }
 
-asmlinkage ssize_t
-compat_sys_writev(unsigned long fd, const struct compat_iovec __user *vec, unsigned long vlen)
+static size_t compat_writev(struct file *file, const struct compat_iovec __user *vec,
+                            unsigned long vlen, loff_t *pos)
 {
-	struct file *file;
 	ssize_t ret = -EBADF;
 
-	file = fget(fd);
-	if (!file)
-		return -EBADF;
 	if (!(file->f_mode & FMODE_WRITE))
 		goto out;
 
@@ -1218,16 +1214,29 @@ compat_sys_writev(unsigned long fd, const struct compat_iovec __user *vec, unsig
 	if (!file->f_op || (!file->f_op->aio_write && !file->f_op->write))
 		goto out;
 
-	ret = compat_do_readv_writev(WRITE, file, vec, vlen, &file->f_pos);
+	ret = compat_do_readv_writev(WRITE, file, vec, vlen, pos);
 
 out:
 	if (ret > 0)
 		add_wchar(current, ret);
 	inc_syscw(current);
-	fput(file);
 	return ret;
 }
 
+asmlinkage ssize_t
+compat_sys_writev(unsigned long fd, const struct compat_iovec __user *vec, unsigned long vlen)
+{
+	struct file *file;
+	ssize_t ret;
+
+	file = fget(fd);
+	if (!file)
+		return -EBADF;
+	ret = compat_writev(file, vec, vlen, &file->f_pos);
+        fput(file);
+        return ret;
+}
+
 asmlinkage long
 compat_sys_vmsplice(int fd, const struct compat_iovec __user *iov32,
 		    unsigned int nr_segs, unsigned int flags)
-- 
1.5.6.5

[Patch v5 4/6] Add preadv and pwritev system calls.

[y]

From: Gerd Hoffmann <kraxel@redhat.com>

This patch adds preadv and pwritev system calls.  These syscalls are a
pretty straightforward combination of pread and readv (same for write).
They are quite useful for doing vectored I/O in threaded applications.
Using lseek+readv instead opens race windows you'll have to plug with
locking.

Other systems have such system calls too, for example NetBSD, check
here: http://www.daemon-systems.org/man/preadv.2.html

The application-visible interface provided by glibc should look like
this to be compatible to the existing implementations in the *BSD family:

  ssize_t preadv(int d, const struct iovec *iov, int iovcnt, off_t offset);
  ssize_t pwritev(int d, const struct iovec *iov, int iovcnt, off_t offset);

This prototype has one problem though:  On 32bit archs is the (64bit)
offset argument unaligned, which the syscall ABI of several archs
doesn't allow to do.  At least s390 needs a wrapper in glibc to handle
this.  As we'll need a wrappers in glibc anyway I've decided to push
problem to glibc entriely and use a syscall prototype which works
without arch-specific wrappers inside the kernel:  The offset argument
is explicitly splitted into two 32bit values.

The patch sports the actual system call implementation and the windup in
the x86 system call tables.  Other archs follow as separate patches.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 arch/x86/ia32/ia32entry.S          |    2 +
 arch/x86/include/asm/unistd_32.h   |    2 +
 arch/x86/include/asm/unistd_64.h   |    4 +++
 arch/x86/kernel/syscall_table_32.S |    2 +
 fs/compat.c                        |   36 ++++++++++++++++++++++++++
 fs/read_write.c                    |   50 ++++++++++++++++++++++++++++++++++++
 include/linux/syscalls.h           |    4 +++
 7 files changed, 100 insertions(+), 0 deletions(-)

diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
index 256b00b..9a8501b 100644
--- a/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -826,4 +826,6 @@ ia32_sys_call_table:
 	.quad sys_dup3			/* 330 */
 	.quad sys_pipe2
 	.quad sys_inotify_init1
+	.quad compat_sys_preadv
+	.quad compat_sys_pwritev
 ia32_syscall_end:
diff --git a/arch/x86/include/asm/unistd_32.h b/arch/x86/include/asm/unistd_32.h
index f2bba78..6e72d74 100644
--- a/arch/x86/include/asm/unistd_32.h
+++ b/arch/x86/include/asm/unistd_32.h
@@ -338,6 +338,8 @@
 #define __NR_dup3		330
 #define __NR_pipe2		331
 #define __NR_inotify_init1	332
+#define __NR_preadv		333
+#define __NR_pwritev		334
 
 #ifdef __KERNEL__
 
diff --git a/arch/x86/include/asm/unistd_64.h b/arch/x86/include/asm/unistd_64.h
index d2e415e..f818294 100644
--- a/arch/x86/include/asm/unistd_64.h
+++ b/arch/x86/include/asm/unistd_64.h
@@ -653,6 +653,10 @@ __SYSCALL(__NR_dup3, sys_dup3)
 __SYSCALL(__NR_pipe2, sys_pipe2)
 #define __NR_inotify_init1			294
 __SYSCALL(__NR_inotify_init1, sys_inotify_init1)
+#define __NR_preadv				295
+__SYSCALL(__NR_preadv, sys_preadv)
+#define __NR_pwritev				296
+__SYSCALL(__NR_pwritev, sys_pwritev)
 
 
 #ifndef __NO_STUBS
diff --git a/arch/x86/kernel/syscall_table_32.S b/arch/x86/kernel/syscall_table_32.S
index d44395f..a1a5506 100644
--- a/arch/x86/kernel/syscall_table_32.S
+++ b/arch/x86/kernel/syscall_table_32.S
@@ -332,3 +332,5 @@ ENTRY(sys_call_table)
 	.long sys_dup3			/* 330 */
 	.long sys_pipe2
 	.long sys_inotify_init1
+	.long sys_preadv
+	.long sys_pwritev
diff --git a/fs/compat.c b/fs/compat.c
index 1ca314f..4e1fa33 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1202,6 +1202,24 @@ compat_sys_readv(unsigned long fd, const struct compat_iovec __user *vec, unsign
 	return ret;
 }
 
+asmlinkage ssize_t
+compat_sys_preadv(unsigned long fd, const struct compat_iovec __user *vec,
+                  unsigned long vlen, u32 pos_high, u32 pos_low)
+{
+	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
+	struct file *file;
+	ssize_t ret;
+
+	if (pos < 0)
+		return -EINVAL;
+	file = fget(fd);
+	if (!file)
+		return -EBADF;
+	ret = compat_readv(file, vec, vlen, &pos);
+	fput(file);
+	return ret;
+}
+
 static size_t compat_writev(struct file *file, const struct compat_iovec __user *vec,
                             unsigned long vlen, loff_t *pos)
 {
@@ -1237,6 +1255,24 @@ compat_sys_writev(unsigned long fd, const struct compat_iovec __user *vec, unsig
         return ret;
 }
 
+asmlinkage ssize_t
+compat_sys_pwritev(unsigned long fd, const struct compat_iovec __user *vec,
+                   unsigned long vlen, u32 pos_high, u32 pos_low)
+{
+	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
+	struct file *file;
+	ssize_t ret;
+
+	if (pos < 0)
+		return -EINVAL;
+	file = fget(fd);
+	if (!file)
+		return -EBADF;
+	ret = compat_writev(file, vec, vlen, &pos);
+	fput(file);
+	return ret;
+}
+
 asmlinkage long
 compat_sys_vmsplice(int fd, const struct compat_iovec __user *iov32,
 		    unsigned int nr_segs, unsigned int flags)
diff --git a/fs/read_write.c b/fs/read_write.c
index 969a6d9..c72a0d6 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -701,6 +701,56 @@ sys_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
 	return ret;
 }
 
+asmlinkage ssize_t sys_preadv(unsigned long fd, const struct iovec __user *vec,
+                              unsigned long vlen, u32 pos_high, u32 pos_low)
+{
+	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
+	struct file *file;
+	ssize_t ret = -EBADF;
+	int fput_needed;
+
+	if (pos < 0)
+		return -EINVAL;
+
+	file = fget_light(fd, &fput_needed);
+	if (file) {
+		ret = -ESPIPE;
+		if (file->f_mode & FMODE_PREAD)
+			ret = vfs_readv(file, vec, vlen, &pos);
+		fput_light(file, fput_needed);
+	}
+
+	if (ret > 0)
+		add_rchar(current, ret);
+	inc_syscr(current);
+	return ret;
+}
+
+asmlinkage ssize_t sys_pwritev(unsigned long fd, const struct iovec __user *vec,
+                               unsigned long vlen, u32 pos_high, u32 pos_low)
+{
+	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
+	struct file *file;
+	ssize_t ret = -EBADF;
+	int fput_needed;
+
+	if (pos < 0)
+		return -EINVAL;
+
+	file = fget_light(fd, &fput_needed);
+	if (file) {
+		ret = -ESPIPE;
+		if (file->f_mode & FMODE_PWRITE)
+			ret = vfs_writev(file, vec, vlen, &pos);
+		fput_light(file, fput_needed);
+	}
+
+	if (ret > 0)
+		add_wchar(current, ret);
+	inc_syscw(current);
+	return ret;
+}
+
 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
 			   size_t count, loff_t max)
 {
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 04fb47b..39b80b1 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -388,6 +388,10 @@ asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
 				size_t count, loff_t pos);
 asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
 				size_t count, loff_t pos);
+asmlinkage ssize_t sys_preadv(unsigned long fd, const struct iovec __user *vec,
+                              unsigned long vlen, u32 pos_high, u32 pos_low);
+asmlinkage ssize_t sys_pwritev(unsigned long fd, const struct iovec __user *vec,
+                               unsigned long vlen, u32 pos_high, u32 pos_low);
 asmlinkage long sys_getcwd(char __user *buf, unsigned long size);
 asmlinkage long sys_mkdir(const char __user *pathname, int mode);
 asmlinkage long sys_chdir(const char __user *filename);
-- 
1.5.6.5

[Patch v5 5/6] MIPS: Add preadv(2) and pwritev(2) syscalls.

[y]

From: Ralf Baechle <ralf@linux-mips.org>

From: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 arch/mips/include/asm/unistd.h |   18 ++++++++++++------
 arch/mips/kernel/scall32-o32.S |    2 ++
 arch/mips/kernel/scall64-64.S  |    2 ++
 arch/mips/kernel/scall64-n32.S |    2 ++
 arch/mips/kernel/scall64-o32.S |    2 ++
 5 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/arch/mips/include/asm/unistd.h b/arch/mips/include/asm/unistd.h
index a73e153..4000501 100644
--- a/arch/mips/include/asm/unistd.h
+++ b/arch/mips/include/asm/unistd.h
@@ -350,16 +350,18 @@
 #define __NR_dup3			(__NR_Linux + 327)
 #define __NR_pipe2			(__NR_Linux + 328)
 #define __NR_inotify_init1		(__NR_Linux + 329)
+#define __NR_preadv			(__NR_Linux + 330)
+#define __NR_pwritev			(__NR_Linux + 331)
 
 /*
  * Offset of the last Linux o32 flavoured syscall
  */
-#define __NR_Linux_syscalls		329
+#define __NR_Linux_syscalls		331
 
 #endif /* _MIPS_SIM == _MIPS_SIM_ABI32 */
 
 #define __NR_O32_Linux			4000
-#define __NR_O32_Linux_syscalls		329
+#define __NR_O32_Linux_syscalls		331
 
 #if _MIPS_SIM == _MIPS_SIM_ABI64
 
@@ -656,16 +658,18 @@
 #define __NR_dup3			(__NR_Linux + 286)
 #define __NR_pipe2			(__NR_Linux + 287)
 #define __NR_inotify_init1		(__NR_Linux + 288)
+#define __NR_preadv			(__NR_Linux + 289)
+#define __NR_pwritev			(__NR_Linux + 290)
 
 /*
  * Offset of the last Linux 64-bit flavoured syscall
  */
-#define __NR_Linux_syscalls		288
+#define __NR_Linux_syscalls		290
 
 #endif /* _MIPS_SIM == _MIPS_SIM_ABI64 */
 
 #define __NR_64_Linux			5000
-#define __NR_64_Linux_syscalls		288
+#define __NR_64_Linux_syscalls		290
 
 #if _MIPS_SIM == _MIPS_SIM_NABI32
 
@@ -966,16 +970,18 @@
 #define __NR_dup3			(__NR_Linux + 290)
 #define __NR_pipe2			(__NR_Linux + 291)
 #define __NR_inotify_init1		(__NR_Linux + 292)
+#define __NR_preadv			(__NR_Linux + 293)
+#define __NR_pwritev			(__NR_Linux + 294)
 
 /*
  * Offset of the last N32 flavoured syscall
  */
-#define __NR_Linux_syscalls		292
+#define __NR_Linux_syscalls		294
 
 #endif /* _MIPS_SIM == _MIPS_SIM_NABI32 */
 
 #define __NR_N32_Linux			6000
-#define __NR_N32_Linux_syscalls		292
+#define __NR_N32_Linux_syscalls		294
 
 #ifdef __KERNEL__
 
diff --git a/arch/mips/kernel/scall32-o32.S b/arch/mips/kernel/scall32-o32.S
index d0916a5..4a8b3e8 100644
--- a/arch/mips/kernel/scall32-o32.S
+++ b/arch/mips/kernel/scall32-o32.S
@@ -650,6 +650,8 @@ einval:	li	v0, -ENOSYS
 	sys	sys_dup3		3
 	sys	sys_pipe2		2
 	sys	sys_inotify_init1	1
+	sys	sys_preadv		6	/* 4330 */
+	sys	sys_pwritev		6
 	.endm
 
 	/* We pre-compute the number of _instruction_ bytes needed to
diff --git a/arch/mips/kernel/scall64-64.S b/arch/mips/kernel/scall64-64.S
index a9e1716..217e3ce 100644
--- a/arch/mips/kernel/scall64-64.S
+++ b/arch/mips/kernel/scall64-64.S
@@ -487,4 +487,6 @@ sys_call_table:
 	PTR	sys_dup3
 	PTR	sys_pipe2
 	PTR	sys_inotify_init1
+	PTR	sys_preadv
+	PTR	sys_pwritev			/* 5390 */
 	.size	sys_call_table,.-sys_call_table
diff --git a/arch/mips/kernel/scall64-n32.S b/arch/mips/kernel/scall64-n32.S
index 30f3b63..f340963 100644
--- a/arch/mips/kernel/scall64-n32.S
+++ b/arch/mips/kernel/scall64-n32.S
@@ -413,4 +413,6 @@ EXPORT(sysn32_call_table)
 	PTR	sys_dup3			/* 5290 */
 	PTR	sys_pipe2
 	PTR	sys_inotify_init1
+	PTR	sys_preadv
+	PTR	sys_pwritev
 	.size	sysn32_call_table,.-sysn32_call_table
diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
index fefef4a..b1d281a 100644
--- a/arch/mips/kernel/scall64-o32.S
+++ b/arch/mips/kernel/scall64-o32.S
@@ -533,4 +533,6 @@ sys_call_table:
 	PTR	sys_dup3
 	PTR	sys_pipe2
 	PTR	sys_inotify_init1
+	PTR	compat_sys_preadv		/* 4330 */
+	PTR	compat_sys_pwritev
 	.size	sys_call_table,.-sys_call_table
-- 
1.5.6.5

[Patch v5 6/6] switch compat readv/preadv/writev/pwritev from fget to fget_light

[y]

From: Gerd Hoffmann <kraxel@redhat.com>


Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 fs/compat.c |   20 ++++++++++++--------
 1 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/fs/compat.c b/fs/compat.c
index 4e1fa33..8d48705 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1192,13 +1192,14 @@ asmlinkage ssize_t
 compat_sys_readv(unsigned long fd, const struct compat_iovec __user *vec, unsigned long vlen)
 {
 	struct file *file;
+	int fput_needed;
 	ssize_t ret;
 
-	file = fget(fd);
+	file = fget_light(fd, &fput_needed);
 	if (!file)
 		return -EBADF;
 	ret = compat_readv(file, vec, vlen, &file->f_pos);
-	fput(file);
+	fput_light(file, fput_needed);
 	return ret;
 }
 
@@ -1208,15 +1209,16 @@ compat_sys_preadv(unsigned long fd, const struct compat_iovec __user *vec,
 {
 	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
 	struct file *file;
+	int fput_needed;
 	ssize_t ret;
 
 	if (pos < 0)
 		return -EINVAL;
-	file = fget(fd);
+	file = fget_light(fd, &fput_needed);
 	if (!file)
 		return -EBADF;
 	ret = compat_readv(file, vec, vlen, &pos);
-	fput(file);
+	fput_light(file, fput_needed);
 	return ret;
 }
 
@@ -1245,13 +1247,14 @@ asmlinkage ssize_t
 compat_sys_writev(unsigned long fd, const struct compat_iovec __user *vec, unsigned long vlen)
 {
 	struct file *file;
+	int fput_needed;
 	ssize_t ret;
 
-	file = fget(fd);
+	file = fget_light(fd, &fput_needed);
 	if (!file)
 		return -EBADF;
 	ret = compat_writev(file, vec, vlen, &file->f_pos);
-        fput(file);
+        fput_light(file, fput_needed);
         return ret;
 }
 
@@ -1261,15 +1264,16 @@ compat_sys_pwritev(unsigned long fd, const struct compat_iovec __user *vec,
 {
 	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
 	struct file *file;
+	int fput_needed;
 	ssize_t ret;
 
 	if (pos < 0)
 		return -EINVAL;
-	file = fget(fd);
+	file = fget_light(fd, &fput_needed);
 	if (!file)
 		return -EBADF;
 	ret = compat_writev(file, vec, vlen, &pos);
-	fput(file);
+	fput_light(file, fput_needed);
 	return ret;
 }
 
-- 
1.5.6.5

Re: [PATCH v5 0/6] Add preadv & pwritev system calls.

[Gerd Hoffmann]

y@redhat.com wrote:
> From: Gerd Hoffmann <kraxel@redhat.com>

Damn, acked git-send-email prompting for the email addr with 'y' instead
of just tapping enter.

The bad thing is that 'reply' doesn't work.

The good thing is that git-send-email added my address to every mail
sent out, so you should be able to figure nevertheless.

Really time for some vacation days.

Happy x-mas everybody and sorry for the inconvenience,

  Gerd