Hi,
I was trying to add support for preadv()/pwritev() for threaded
databases. Currently the patch is in -mm tree.
http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.15-
rc5/2.6.15-rc5-mm3/broken-out/support-for-preadv-pwritev.patch
This needs a new set of system calls. Ulrich Drepper pointed out
that, instead of adding a system call for the limited functionality
it provides, why not we add new iovec interface as follows (offset-per-
segment) which provides greater functionality & flexibility.
+struct niovec
+{
+ void __user *iov_base;
+ __kernel_size_t iov_len;
+ __kernel_loff_t iov_off; /* NEW */
+};
In order to support this, we need to change all the file_operations
(readv/writev) and its helper functions to take this new structure.
I took a stab at doing it and I want feedback on whether this is
acceptable. All the patch does - is to make kernel use new structure,
but the existing syscalls like readv()/writev() still deals with
original one to keep the compatibility. (pipes and sockets need
changing too - which I have not addressed yet).
Is this the right approach ?
Please DO NOT apply (I haven't tested it at all).
Thanks,
Badari
diff -Narup -X dontdiff linux-2.6.15-rc5/fs/direct-io.c linux-2.6.15-rc5.vec/fs/direct-io.c
--- linux-2.6.15-rc5/fs/direct-io.c 2005-12-03 21:10:42.000000000 -0800
+++ linux-2.6.15-rc5.vec/fs/direct-io.c 2005-12-19 13:23:18.000000000 -0800
@@ -934,7 +934,7 @@ out:
*/
static ssize_t
direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
- const struct iovec *iov, loff_t offset, unsigned long nr_segs,
+ const struct niovec *iov, loff_t offset, unsigned long nr_segs,
unsigned blkbits, get_blocks_t get_blocks, dio_iodone_t end_io,
struct dio *dio)
{
@@ -1162,7 +1162,7 @@ direct_io_worker(int rw, struct kiocb *i
*/
ssize_t
__blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
- struct block_device *bdev, const struct iovec *iov, loff_t offset,
+ struct block_device *bdev, const struct niovec *iov, loff_t offset,
unsigned long nr_segs, get_blocks_t get_blocks, dio_iodone_t end_io,
int dio_lock_type)
{
diff -Narup -X dontdiff linux-2.6.15-rc5/fs/read_write.c linux-2.6.15-rc5.vec/fs/read_write.c
--- linux-2.6.15-rc5/fs/read_write.c 2005-12-03 21:10:42.000000000 -0800
+++ linux-2.6.15-rc5.vec/fs/read_write.c 2005-12-19 12:53:42.000000000 -0800
@@ -405,7 +405,7 @@ asmlinkage ssize_t sys_pwrite64(unsigned
/*
* Reduce an iovec's length in-place. Return the resulting number of segments
*/
-unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
+unsigned long iov_shorten(struct niovec *iov, unsigned long nr_segs, size_t to)
{
unsigned long seg = 0;
size_t len = 0;
@@ -424,6 +424,20 @@ unsigned long iov_shorten(struct iovec *
EXPORT_SYMBOL(iov_shorten);
+static int copy_from_user_iovec(struct niovec *iov,
+ const struct iovec __user * uvector,
+ unsigned long nr_segs)
+{
+ while (nr_segs--) {
+ if (copy_from_user(iov, uvector, sizeof(struct iovec)))
+ return -EFAULT;
+
+ iov++;
+ uvector++;
+ }
+ return 0;
+}
+
/* A write operation does a read from user space and vice versa */
#define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
@@ -432,15 +446,16 @@ static ssize_t do_readv_writev(int type,
unsigned long nr_segs, loff_t *pos)
{
typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
- typedef ssize_t (*iov_fn_t)(struct file *, const struct iovec *, unsigned long, loff_t *);
+ typedef ssize_t (*iov_fn_t)(struct file *, const struct niovec *, unsigned long, loff_t *);
size_t tot_len;
- struct iovec iovstack[UIO_FASTIOV];
- struct iovec *iov=iovstack, *vector;
+ struct niovec iovstack[UIO_FASTIOV];
+ struct niovec *iov=iovstack, *vector;
ssize_t ret;
int seg;
io_fn_t fn;
iov_fn_t fnv;
+ loff_t opos;
/*
* SuS says "The readv() function *may* fail if the iovcnt argument
@@ -462,12 +477,12 @@ static ssize_t do_readv_writev(int type,
goto out;
if (nr_segs > UIO_FASTIOV) {
ret = -ENOMEM;
- iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
+ iov = kmalloc(nr_segs*sizeof(struct niovec), GFP_KERNEL);
if (!iov)
goto out;
}
- ret = -EFAULT;
- if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector)))
+ ret = copy_from_user_iovec(iov, uvector, nr_segs);
+ if (ret)
goto out;
/*
@@ -478,6 +493,7 @@ static ssize_t do_readv_writev(int type,
* Be careful here because iov_len is a size_t not an ssize_t
*/
tot_len = 0;
+ opos = *pos;
ret = -EINVAL;
for (seg = 0; seg < nr_segs; seg++) {
void __user *buf = iov[seg].iov_base;
@@ -487,7 +503,9 @@ static ssize_t do_readv_writev(int type,
goto out;
if (unlikely(!access_ok(vrfy_dir(type), buf, len)))
goto Efault;
+ iov[seg].iov_off = opos;
tot_len += len;
+ opos += len;
if ((ssize_t)tot_len < 0) /* maths overflow on the ssize_t */
goto out;
}
diff -Narup -X dontdiff linux-2.6.15-rc5/include/linux/fs.h linux-2.6.15-rc5.vec/include/linux/fs.h
--- linux-2.6.15-rc5/include/linux/fs.h 2005-12-03 21:10:42.000000000 -0800
+++ linux-2.6.15-rc5.vec/include/linux/fs.h 2005-12-19 12:03:25.000000000 -0800
@@ -226,6 +226,7 @@ extern int dir_notify_enable;
#include <asm/byteorder.h>
struct iovec;
+struct niovec;
struct nameidata;
struct kiocb;
struct pipe_inode_info;
@@ -333,7 +334,7 @@ struct address_space_operations {
sector_t (*bmap)(struct address_space *, sector_t);
int (*invalidatepage) (struct page *, unsigned long);
int (*releasepage) (struct page *, gfp_t);
- ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
+ ssize_t (*direct_IO)(int, struct kiocb *, const struct niovec *iov,
loff_t offset, unsigned long nr_segs);
struct page* (*get_xip_page)(struct address_space *, sector_t,
int);
@@ -987,8 +988,8 @@ struct file_operations {
int (*aio_fsync) (struct kiocb *, int datasync);
int (*fasync) (int, struct file *, int);
int (*lock) (struct file *, int, struct file_lock *);
- ssize_t (*readv) (struct file *, const struct iovec *, unsigned long, loff_t *);
- ssize_t (*writev) (struct file *, const struct iovec *, unsigned long, loff_t *);
+ ssize_t (*readv) (struct file *, const struct niovec *, unsigned long, loff_t *);
+ ssize_t (*writev) (struct file *, const struct niovec *, unsigned long, loff_t *);
ssize_t (*sendfile) (struct file *, loff_t *, size_t, read_actor_t, void *);
ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
@@ -1522,17 +1523,17 @@ extern ssize_t generic_file_read(struct
int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk);
extern ssize_t generic_file_write(struct file *, const char __user *, size_t, loff_t *);
extern ssize_t generic_file_aio_read(struct kiocb *, char __user *, size_t, loff_t);
-extern ssize_t __generic_file_aio_read(struct kiocb *, const struct iovec *, unsigned long, loff_t *);
+extern ssize_t __generic_file_aio_read(struct kiocb *, const struct niovec *, unsigned long, loff_t *);
extern ssize_t generic_file_aio_write(struct kiocb *, const char __user *, size_t, loff_t);
-extern ssize_t generic_file_aio_write_nolock(struct kiocb *, const struct iovec *,
+extern ssize_t generic_file_aio_write_nolock(struct kiocb *, const struct niovec *,
unsigned long, loff_t *);
-extern ssize_t generic_file_direct_write(struct kiocb *, const struct iovec *,
+extern ssize_t generic_file_direct_write(struct kiocb *, const struct niovec *,
unsigned long *, loff_t, loff_t *, size_t, size_t);
-extern ssize_t generic_file_buffered_write(struct kiocb *, const struct iovec *,
+extern ssize_t generic_file_buffered_write(struct kiocb *, const struct niovec *,
unsigned long, loff_t, loff_t *, size_t, ssize_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);
-ssize_t generic_file_write_nolock(struct file *file, const struct iovec *iov,
+ssize_t generic_file_write_nolock(struct file *file, const struct niovec *iov,
unsigned long nr_segs, loff_t *ppos);
extern ssize_t generic_file_sendfile(struct file *, loff_t *, size_t, read_actor_t, void *);
extern void do_generic_mapping_read(struct address_space *mapping,
@@ -1540,9 +1541,9 @@ extern void do_generic_mapping_read(stru
loff_t *, read_descriptor_t *, read_actor_t);
extern void
file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
-extern ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
+extern ssize_t generic_file_readv(struct file *filp, const struct niovec *iov,
unsigned long nr_segs, loff_t *ppos);
-ssize_t generic_file_writev(struct file *filp, const struct iovec *iov,
+ssize_t generic_file_writev(struct file *filp, const struct niovec *iov,
unsigned long nr_segs, loff_t *ppos);
extern loff_t no_llseek(struct file *file, loff_t offset, int origin);
extern loff_t generic_file_llseek(struct file *file, loff_t offset, int origin);
@@ -1580,7 +1581,7 @@ static inline void do_generic_file_read(
}
ssize_t __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
- struct block_device *bdev, const struct iovec *iov, loff_t offset,
+ struct block_device *bdev, const struct niovec *iov, loff_t offset,
unsigned long nr_segs, get_blocks_t get_blocks, dio_iodone_t end_io,
int lock_type);
@@ -1591,7 +1592,7 @@ enum {
};
static inline ssize_t blockdev_direct_IO(int rw, struct kiocb *iocb,
- struct inode *inode, struct block_device *bdev, const struct iovec *iov,
+ struct inode *inode, struct block_device *bdev, const struct niovec *iov,
loff_t offset, unsigned long nr_segs, get_blocks_t get_blocks,
dio_iodone_t end_io)
{
@@ -1600,7 +1601,7 @@ static inline ssize_t blockdev_direct_IO
}
static inline ssize_t blockdev_direct_IO_no_locking(int rw, struct kiocb *iocb,
- struct inode *inode, struct block_device *bdev, const struct iovec *iov,
+ struct inode *inode, struct block_device *bdev, const struct niovec *iov,
loff_t offset, unsigned long nr_segs, get_blocks_t get_blocks,
dio_iodone_t end_io)
{
@@ -1609,7 +1610,7 @@ static inline ssize_t blockdev_direct_IO
}
static inline ssize_t blockdev_direct_IO_own_locking(int rw, struct kiocb *iocb,
- struct inode *inode, struct block_device *bdev, const struct iovec *iov,
+ struct inode *inode, struct block_device *bdev, const struct niovec *iov,
loff_t offset, unsigned long nr_segs, get_blocks_t get_blocks,
dio_iodone_t end_io)
{
diff -Narup -X dontdiff linux-2.6.15-rc5/include/linux/uio.h linux-2.6.15-rc5.vec/include/linux/uio.h
--- linux-2.6.15-rc5/include/linux/uio.h 2005-12-03 21:10:42.000000000 -0800
+++ linux-2.6.15-rc5.vec/include/linux/uio.h 2005-12-19 12:51:19.000000000 -0800
@@ -23,6 +23,14 @@ struct iovec
__kernel_size_t iov_len; /* Must be size_t (1003.1g) */
};
+
+struct niovec
+{
+ void __user *iov_base;
+ __kernel_size_t iov_len;
+ __kernel_loff_t iov_off;
+};
+
#ifdef __KERNEL__
struct kvec {
@@ -51,7 +59,7 @@ struct kvec {
* segment lengths have been validated. Because the individual lengths can
* overflow a size_t when added together.
*/
-static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
+static inline size_t iov_length(const struct niovec *iov, unsigned long nr_segs)
{
unsigned long seg;
size_t ret = 0;
@@ -61,6 +69,6 @@ static inline size_t iov_length(const st
return ret;
}
-unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
+unsigned long iov_shorten(struct niovec *iov, unsigned long nr_segs, size_t to);
#endif
diff -Narup -X dontdiff linux-2.6.15-rc5/mm/filemap.c linux-2.6.15-rc5.vec/mm/filemap.c
--- linux-2.6.15-rc5/mm/filemap.c 2005-12-03 21:10:42.000000000 -0800
+++ linux-2.6.15-rc5.vec/mm/filemap.c 2005-12-19 12:50:53.000000000 -0800
@@ -38,7 +38,7 @@
#include <asm/mman.h>
static ssize_t
-generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
+generic_file_direct_IO(int rw, struct kiocb *iocb, const struct niovec *iov,
loff_t offset, unsigned long nr_segs);
/*
@@ -965,7 +965,7 @@ success:
* that can use the page cache directly.
*/
ssize_t
-__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
+__generic_file_aio_read(struct kiocb *iocb, const struct niovec *iov,
unsigned long nr_segs, loff_t *ppos)
{
struct file *filp = iocb->ki_filp;
@@ -975,7 +975,7 @@ __generic_file_aio_read(struct kiocb *io
count = 0;
for (seg = 0; seg < nr_segs; seg++) {
- const struct iovec *iv = &iov[seg];
+ const struct niovec *iv = &iov[seg];
/*
* If any segment has a negative length, or the cumulative
@@ -1045,7 +1045,7 @@ EXPORT_SYMBOL(__generic_file_aio_read);
ssize_t
generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
{
- struct iovec local_iov = { .iov_base = buf, .iov_len = count };
+ struct niovec local_iov = { .iov_base = buf, .iov_len = count };
BUG_ON(iocb->ki_pos != pos);
return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
@@ -1056,7 +1056,7 @@ EXPORT_SYMBOL(generic_file_aio_read);
ssize_t
generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
{
- struct iovec local_iov = { .iov_base = buf, .iov_len = count };
+ struct niovec local_iov = { .iov_base = buf, .iov_len = count };
struct kiocb kiocb;
ssize_t ret;
@@ -1727,7 +1727,7 @@ EXPORT_SYMBOL(remove_suid);
size_t
__filemap_copy_from_user_iovec(char *vaddr,
- const struct iovec *iov, size_t base, size_t bytes)
+ const struct niovec *iov, size_t base, size_t bytes)
{
size_t copied = 0, left = 0;
@@ -1833,7 +1833,7 @@ inline int generic_write_checks(struct f
EXPORT_SYMBOL(generic_write_checks);
ssize_t
-generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
+generic_file_direct_write(struct kiocb *iocb, const struct niovec *iov,
unsigned long *nr_segs, loff_t pos, loff_t *ppos,
size_t count, size_t ocount)
{
@@ -1843,7 +1843,7 @@ generic_file_direct_write(struct kiocb *
ssize_t written;
if (count != ocount)
- *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
+ *nr_segs = iov_shorten((struct niovec *)iov, *nr_segs, count);
written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
if (written > 0) {
@@ -1873,7 +1873,7 @@ generic_file_direct_write(struct kiocb *
EXPORT_SYMBOL(generic_file_direct_write);
ssize_t
-generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
+generic_file_buffered_write(struct kiocb *iocb, const struct niovec *iov,
unsigned long nr_segs, loff_t pos, loff_t *ppos,
size_t count, ssize_t written)
{
@@ -1886,7 +1886,7 @@ generic_file_buffered_write(struct kiocb
struct page *cached_page = NULL;
size_t bytes;
struct pagevec lru_pvec;
- const struct iovec *cur_iov = iov; /* current iovec */
+ const struct niovec *cur_iov = iov; /* current iovec */
size_t iov_base = 0; /* offset in the current iovec */
char __user *buf;
@@ -2013,7 +2013,7 @@ generic_file_buffered_write(struct kiocb
EXPORT_SYMBOL(generic_file_buffered_write);
static ssize_t
-__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
+__generic_file_aio_write_nolock(struct kiocb *iocb, const struct niovec *iov,
unsigned long nr_segs, loff_t *ppos)
{
struct file *file = iocb->ki_filp;
@@ -2028,7 +2028,7 @@ __generic_file_aio_write_nolock(struct k
ocount = 0;
for (seg = 0; seg < nr_segs; seg++) {
- const struct iovec *iv = &iov[seg];
+ const struct niovec *iv = &iov[seg];
/*
* If any segment has a negative length, or the cumulative
@@ -2091,7 +2091,7 @@ out:
EXPORT_SYMBOL(generic_file_aio_write_nolock);
ssize_t
-generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
+generic_file_aio_write_nolock(struct kiocb *iocb, const struct niovec *iov,
unsigned long nr_segs, loff_t *ppos)
{
struct file *file = iocb->ki_filp;
@@ -2113,7 +2113,7 @@ generic_file_aio_write_nolock(struct kio
}
static ssize_t
-__generic_file_write_nolock(struct file *file, const struct iovec *iov,
+__generic_file_write_nolock(struct file *file, const struct niovec *iov,
unsigned long nr_segs, loff_t *ppos)
{
struct kiocb kiocb;
@@ -2127,7 +2127,7 @@ __generic_file_write_nolock(struct file
}
ssize_t
-generic_file_write_nolock(struct file *file, const struct iovec *iov,
+generic_file_write_nolock(struct file *file, const struct niovec *iov,
unsigned long nr_segs, loff_t *ppos)
{
struct kiocb kiocb;
@@ -2148,7 +2148,7 @@ ssize_t generic_file_aio_write(struct ki
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
ssize_t ret;
- struct iovec local_iov = { .iov_base = (void __user *)buf,
+ struct niovec local_iov = { .iov_base = (void __user *)buf,
.iov_len = count };
BUG_ON(iocb->ki_pos != pos);
@@ -2175,7 +2175,7 @@ ssize_t generic_file_write(struct file *
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
ssize_t ret;
- struct iovec local_iov = { .iov_base = (void __user *)buf,
+ struct niovec local_iov = { .iov_base = (void __user *)buf,
.iov_len = count };
down(&inode->i_sem);
@@ -2193,7 +2193,7 @@ ssize_t generic_file_write(struct file *
}
EXPORT_SYMBOL(generic_file_write);
-ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
+ssize_t generic_file_readv(struct file *filp, const struct niovec *iov,
unsigned long nr_segs, loff_t *ppos)
{
struct kiocb kiocb;
@@ -2207,7 +2207,7 @@ ssize_t generic_file_readv(struct file *
}
EXPORT_SYMBOL(generic_file_readv);
-ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
+ssize_t generic_file_writev(struct file *file, const struct niovec *iov,
unsigned long nr_segs, loff_t *ppos)
{
struct address_space *mapping = file->f_mapping;
@@ -2234,7 +2234,7 @@ EXPORT_SYMBOL(generic_file_writev);
* went wrong during pagecache shootdown.
*/
static ssize_t
-generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
+generic_file_direct_IO(int rw, struct kiocb *iocb, const struct niovec *iov,
loff_t offset, unsigned long nr_segs)
{
struct file *file = iocb->ki_filp;
diff -Narup -X dontdiff linux-2.6.15-rc5/mm/filemap.h linux-2.6.15-rc5.vec/mm/filemap.h
--- linux-2.6.15-rc5/mm/filemap.h 2005-12-03 21:10:42.000000000 -0800
+++ linux-2.6.15-rc5.vec/mm/filemap.h 2005-12-19 13:22:40.000000000 -0800
@@ -17,7 +17,7 @@
size_t
__filemap_copy_from_user_iovec(char *vaddr,
- const struct iovec *iov,
+ const struct niovec *iov,
size_t base,
size_t bytes);
@@ -54,7 +54,7 @@ filemap_copy_from_user(struct page *page
*/
static inline size_t
filemap_copy_from_user_iovec(struct page *page, unsigned long offset,
- const struct iovec *iov, size_t base, size_t bytes)
+ const struct niovec *iov, size_t base, size_t bytes)
{
char *kaddr;
size_t copied;
@@ -73,9 +73,9 @@ filemap_copy_from_user_iovec(struct page
}
static inline void
-filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
+filemap_set_next_iovec(const struct niovec **iovp, size_t *basep, size_t bytes)
{
- const struct iovec *iov = *iovp;
+ const struct niovec *iov = *iovp;
size_t base = *basep;
while (bytes) {
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