[PATCH V9 06/33] iov_iter: hide iovec details behind ops function pointers

From: Dave Kleikamp
Date: Wed Oct 16 2013 - 10:15:30 EST

Next message: Dave Kleikamp: "[PATCH V9 33/33] tmpfs: add support for read_iter and write_iter"
Previous message: Nicolas Ferre: "Re: [PATCH] pinctrl: at91: correct a few typos"
In reply to: Dave Kleikamp: "[PATCH V9 20/33] fs: add read_iter and write_iter to several file systems"
Next in thread: Dave Kleikamp: "[PATCH V9 33/33] tmpfs: add support for read_iter and write_iter"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

From: Zach Brown <zab@xxxxxxxxx>

This moves the current iov_iter functions behind an ops struct of
function pointers. The current iov_iter functions all work with memory
which is specified by iovec arrays of user space pointers.

This patch is part of a series that lets us specify memory with bio_vec
arrays of page pointers. By moving to an iov_iter operation struct we
can add that support in later patches in this series by adding another
set of function pointers.

I only came to this after having initialy tried to teach the current
iov_iter functions about bio_vecs by introducing conditional branches
that dealt with bio_vecs in all the functions. It wasn't pretty. This
approach seems to be the lesser evil.

Signed-off-by: Zach Brown <zab@xxxxxxxxx>
Signed-off-by: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
---
fs/cifs/file.c | 4 +--
fs/fuse/file.c | 5 ++--
fs/iov-iter.c | 86 +++++++++++++++++++++++++++++-------------------------
include/linux/fs.h | 77 ++++++++++++++++++++++++++++++++++++++----------
4 files changed, 114 insertions(+), 58 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 7ddddf2..cf6aedc 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2737,8 +2737,8 @@ cifs_readdata_to_iov(struct cifs_readdata *rdata, const struct iovec *iov,
/* go while there's data to be copied and no errors */
if (copy && !rc) {
pdata = kmap(page);
- rc = memcpy_toiovecend(ii.iov, pdata, ii.iov_offset,
- (int)copy);
+ rc = memcpy_toiovecend(iov_iter_iovec(&ii), pdata,
+ ii.iov_offset, (int)copy);
kunmap(page);
if (!rc) {
*copied += copy;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 606ff63..b04c8c6 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1178,9 +1178,10 @@ static inline void fuse_page_descs_length_init(struct fuse_req *req,
req->page_descs[i].offset;
}

-static inline unsigned long fuse_get_user_addr(const struct iov_iter *ii)
+static inline unsigned long fuse_get_user_addr(struct iov_iter *ii)
{
- return (unsigned long)ii->iov->iov_base + ii->iov_offset;
+ struct iovec *iov = iov_iter_iovec(ii);
+ return (unsigned long)iov->iov_base + ii->iov_offset;
}

static inline size_t fuse_get_frag_size(const struct iov_iter *ii,
diff --git a/fs/iov-iter.c b/fs/iov-iter.c
index 6cecab4..6cb6be0 100644
--- a/fs/iov-iter.c
+++ b/fs/iov-iter.c
@@ -36,9 +36,10 @@ static size_t __iovec_copy_to_user(char *vaddr, const struct iovec *iov,
* were sucessfully copied. If a fault is encountered then return the number of
* bytes which were copied.
*/
-size_t iov_iter_copy_to_user_atomic(struct page *page,
+static size_t ii_iovec_copy_to_user_atomic(struct page *page,
struct iov_iter *i, unsigned long offset, size_t bytes)
{
+ struct iovec *iov = (struct iovec *)i->data;
char *kaddr;
size_t copied;

@@ -46,55 +47,52 @@ size_t iov_iter_copy_to_user_atomic(struct page *page,
kaddr = kmap_atomic(page);
if (likely(i->nr_segs == 1)) {
int left;
- char __user *buf = i->iov->iov_base + i->iov_offset;
+ char __user *buf = iov->iov_base + i->iov_offset;
left = __copy_to_user_inatomic(buf, kaddr + offset, bytes);
copied = bytes - left;
} else {
- copied = __iovec_copy_to_user(kaddr + offset, i->iov,
+ copied = __iovec_copy_to_user(kaddr + offset, iov,
i->iov_offset, bytes, 1);
}
kunmap_atomic(kaddr);

return copied;
}
-EXPORT_SYMBOL(iov_iter_copy_to_user_atomic);

/*
* This has the same sideeffects and return value as
- * iov_iter_copy_to_user_atomic().
+ * ii_iovec_copy_to_user_atomic().
* The difference is that it attempts to resolve faults.
* Page must not be locked.
*/
-size_t __iov_iter_copy_to_user(struct page *page,
- struct iov_iter *i, unsigned long offset, size_t bytes)
+static size_t ii_iovec_copy_to_user(struct page *page,
+ struct iov_iter *i, unsigned long offset, size_t bytes,
+ int check_access)
{
+ struct iovec *iov = (struct iovec *)i->data;
char *kaddr;
size_t copied;

+ if (check_access) {
+ might_sleep();
+ if (generic_segment_checks(iov, &i->nr_segs, &bytes,
+ VERIFY_WRITE))
+ return 0;
+ }
+
kaddr = kmap(page);
if (likely(i->nr_segs == 1)) {
int left;
- char __user *buf = i->iov->iov_base + i->iov_offset;
+ char __user *buf = iov->iov_base + i->iov_offset;
left = copy_to_user(buf, kaddr + offset, bytes);
copied = bytes - left;
} else {
- copied = __iovec_copy_to_user(kaddr + offset, i->iov,
+ copied = __iovec_copy_to_user(kaddr + offset, iov,
i->iov_offset, bytes, 0);
}
kunmap(page);
return copied;
}
-EXPORT_SYMBOL(__iov_iter_copy_to_user);
-
-size_t iov_iter_copy_to_user(struct page *page,
- struct iov_iter *i, unsigned long offset, size_t bytes)
-{
- might_sleep();
- if (generic_segment_checks(i->iov, &i->nr_segs, &bytes, VERIFY_WRITE))
- return 0;
- return __iov_iter_copy_to_user(page, i, offset, bytes);
-}
-EXPORT_SYMBOL(iov_iter_copy_to_user);

static size_t __iovec_copy_from_user(char *vaddr, const struct iovec *iov,
size_t base, size_t bytes, int atomic)
@@ -126,9 +124,10 @@ static size_t __iovec_copy_from_user(char *vaddr, const struct iovec *iov,
* were successfully copied. If a fault is encountered then return the number
* of bytes which were copied.
*/
-size_t iov_iter_copy_from_user_atomic(struct page *page,
+static size_t ii_iovec_copy_from_user_atomic(struct page *page,
struct iov_iter *i, unsigned long offset, size_t bytes)
{
+ struct iovec *iov = (struct iovec *)i->data;
char *kaddr;
size_t copied;

@@ -136,11 +135,11 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
kaddr = kmap_atomic(page);
if (likely(i->nr_segs == 1)) {
int left;
- char __user *buf = i->iov->iov_base + i->iov_offset;
+ char __user *buf = iov->iov_base + i->iov_offset;
left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
copied = bytes - left;
} else {
- copied = __iovec_copy_from_user(kaddr + offset, i->iov,
+ copied = __iovec_copy_from_user(kaddr + offset, iov,
i->iov_offset, bytes, 1);
}
kunmap_atomic(kaddr);
@@ -151,32 +150,32 @@ EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);

/*
* This has the same sideeffects and return value as
- * iov_iter_copy_from_user_atomic().
+ * ii_iovec_copy_from_user_atomic().
* The difference is that it attempts to resolve faults.
* Page must not be locked.
*/
-size_t iov_iter_copy_from_user(struct page *page,
+static size_t ii_iovec_copy_from_user(struct page *page,
struct iov_iter *i, unsigned long offset, size_t bytes)
{
+ struct iovec *iov = (struct iovec *)i->data;
char *kaddr;
size_t copied;

kaddr = kmap(page);
if (likely(i->nr_segs == 1)) {
int left;
- char __user *buf = i->iov->iov_base + i->iov_offset;
+ char __user *buf = iov->iov_base + i->iov_offset;
left = __copy_from_user(kaddr + offset, buf, bytes);
copied = bytes - left;
} else {
- copied = __iovec_copy_from_user(kaddr + offset, i->iov,
+ copied = __iovec_copy_from_user(kaddr + offset, iov,
i->iov_offset, bytes, 0);
}
kunmap(page);
return copied;
}
-EXPORT_SYMBOL(iov_iter_copy_from_user);

-void iov_iter_advance(struct iov_iter *i, size_t bytes)
+static void ii_iovec_advance(struct iov_iter *i, size_t bytes)
{
BUG_ON(i->count < bytes);

@@ -184,7 +183,7 @@ void iov_iter_advance(struct iov_iter *i, size_t bytes)
i->iov_offset += bytes;
i->count -= bytes;
} else {
- const struct iovec *iov = i->iov;
+ struct iovec *iov = (struct iovec *)i->data;
size_t base = i->iov_offset;
unsigned long nr_segs = i->nr_segs;

@@ -206,12 +205,11 @@ void iov_iter_advance(struct iov_iter *i, size_t bytes)
base = 0;
}
}
- i->iov = iov;
+ i->data = (unsigned long)iov;
i->iov_offset = base;
i->nr_segs = nr_segs;
}
}
-EXPORT_SYMBOL(iov_iter_advance);

/*
* Fault in the first iovec of the given iov_iter, to a maximum length
@@ -222,23 +220,33 @@ EXPORT_SYMBOL(iov_iter_advance);
* would be possible (callers must not rely on the fact that _only_ the
* first iovec will be faulted with the current implementation).
*/
-int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
+static int ii_iovec_fault_in_readable(struct iov_iter *i, size_t bytes)
{
- char __user *buf = i->iov->iov_base + i->iov_offset;
- bytes = min(bytes, i->iov->iov_len - i->iov_offset);
+ struct iovec *iov = (struct iovec *)i->data;
+ char __user *buf = iov->iov_base + i->iov_offset;
+ bytes = min(bytes, iov->iov_len - i->iov_offset);
return fault_in_pages_readable(buf, bytes);
}
-EXPORT_SYMBOL(iov_iter_fault_in_readable);

/*
* Return the count of just the current iov_iter segment.
*/
-size_t iov_iter_single_seg_count(const struct iov_iter *i)
+static size_t ii_iovec_single_seg_count(const struct iov_iter *i)
{
- const struct iovec *iov = i->iov;
+ const struct iovec *iov = (struct iovec *)i->data;
if (i->nr_segs == 1)
return i->count;
else
return min(i->count, iov->iov_len - i->iov_offset);
}
-EXPORT_SYMBOL(iov_iter_single_seg_count);
+
+struct iov_iter_ops ii_iovec_ops = {
+ .ii_copy_to_user_atomic = ii_iovec_copy_to_user_atomic,
+ .ii_copy_to_user = ii_iovec_copy_to_user,
+ .ii_copy_from_user_atomic = ii_iovec_copy_from_user_atomic,
+ .ii_copy_from_user = ii_iovec_copy_from_user,
+ .ii_advance = ii_iovec_advance,
+ .ii_fault_in_readable = ii_iovec_fault_in_readable,
+ .ii_single_seg_count = ii_iovec_single_seg_count,
+};
+EXPORT_SYMBOL(ii_iovec_ops);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b7a0ff8..0137010 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -291,31 +291,73 @@ struct address_space;
struct writeback_control;

struct iov_iter {
- const struct iovec *iov;
+ struct iov_iter_ops *ops;
+ unsigned long data;
unsigned long nr_segs;
size_t iov_offset;
size_t count;
};

-size_t __iov_iter_copy_to_user_atomic(struct page *page,
- struct iov_iter *i, unsigned long offset, size_t bytes);
-size_t __iov_iter_copy_to_user(struct page *page,
- struct iov_iter *i, unsigned long offset, size_t bytes);
-size_t iov_iter_copy_to_user(struct page *page,
- struct iov_iter *i, unsigned long offset, size_t bytes);
-size_t iov_iter_copy_from_user_atomic(struct page *page,
- struct iov_iter *i, unsigned long offset, size_t bytes);
-size_t iov_iter_copy_from_user(struct page *page,
- struct iov_iter *i, unsigned long offset, size_t bytes);
-void iov_iter_advance(struct iov_iter *i, size_t bytes);
-int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
-size_t iov_iter_single_seg_count(const struct iov_iter *i);
+struct iov_iter_ops {
+ size_t (*ii_copy_to_user_atomic)(struct page *, struct iov_iter *,
+ unsigned long, size_t);
+ size_t (*ii_copy_to_user)(struct page *, struct iov_iter *,
+ unsigned long, size_t, int);
+ size_t (*ii_copy_from_user_atomic)(struct page *, struct iov_iter *,
+ unsigned long, size_t);
+ size_t (*ii_copy_from_user)(struct page *, struct iov_iter *,
+ unsigned long, size_t);
+ void (*ii_advance)(struct iov_iter *, size_t);
+ int (*ii_fault_in_readable)(struct iov_iter *, size_t);
+ size_t (*ii_single_seg_count)(const struct iov_iter *);
+};
+
+static inline size_t iov_iter_copy_to_user_atomic(struct page *page,
+ struct iov_iter *i, unsigned long offset, size_t bytes)
+{
+ return i->ops->ii_copy_to_user_atomic(page, i, offset, bytes);
+}
+static inline size_t __iov_iter_copy_to_user(struct page *page,
+ struct iov_iter *i, unsigned long offset, size_t bytes)
+{
+ return i->ops->ii_copy_to_user(page, i, offset, bytes, 0);
+}
+static inline size_t iov_iter_copy_to_user(struct page *page,
+ struct iov_iter *i, unsigned long offset, size_t bytes)
+{
+ return i->ops->ii_copy_to_user(page, i, offset, bytes, 1);
+}
+static inline size_t iov_iter_copy_from_user_atomic(struct page *page,
+ struct iov_iter *i, unsigned long offset, size_t bytes)
+{
+ return i->ops->ii_copy_from_user_atomic(page, i, offset, bytes);
+}
+static inline size_t iov_iter_copy_from_user(struct page *page,
+ struct iov_iter *i, unsigned long offset, size_t bytes)
+{
+ return i->ops->ii_copy_from_user(page, i, offset, bytes);
+}
+static inline void iov_iter_advance(struct iov_iter *i, size_t bytes)
+{
+ return i->ops->ii_advance(i, bytes);
+}
+static inline int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
+{
+ return i->ops->ii_fault_in_readable(i, bytes);
+}
+static inline size_t iov_iter_single_seg_count(const struct iov_iter *i)
+{
+ return i->ops->ii_single_seg_count(i);
+}
+
+extern struct iov_iter_ops ii_iovec_ops;

static inline void iov_iter_init(struct iov_iter *i,
const struct iovec *iov, unsigned long nr_segs,
size_t count, size_t written)
{
- i->iov = iov;
+ i->ops = &ii_iovec_ops;
+ i->data = (unsigned long)iov;
i->nr_segs = nr_segs;
i->iov_offset = 0;
i->count = count + written;
@@ -323,6 +365,11 @@ static inline void iov_iter_init(struct iov_iter *i,
iov_iter_advance(i, written);
}

+static inline struct iovec *iov_iter_iovec(struct iov_iter *i)
+{
+ return (struct iovec *)i->data;
+}
+
static inline size_t iov_iter_count(struct iov_iter *i)
{
return i->count;
--
1.8.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Next message: Dave Kleikamp: "[PATCH V9 33/33] tmpfs: add support for read_iter and write_iter"
Previous message: Nicolas Ferre: "Re: [PATCH] pinctrl: at91: correct a few typos"
In reply to: Dave Kleikamp: "[PATCH V9 20/33] fs: add read_iter and write_iter to several file systems"
Next in thread: Dave Kleikamp: "[PATCH V9 33/33] tmpfs: add support for read_iter and write_iter"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]