From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Kleikamp Subject: [PATCH V8 03/33] iov_iter: add copy_to_user support Date: Thu, 25 Jul 2013 12:50:29 -0500 Message-ID: <1374774659-13121-4-git-send-email-dave.kleikamp@oracle.com> References: <1374774659-13121-1-git-send-email-dave.kleikamp@oracle.com> Cc: linux-fsdevel@vger.kernel.org, Andrew Morton , "Maxim V. Patlasov" , Zach Brown , Dave Kleikamp To: linux-kernel@vger.kernel.org Return-path: In-Reply-To: <1374774659-13121-1-git-send-email-dave.kleikamp@oracle.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org From: Zach Brown This adds iov_iter wrappers around copy_to_user() to match the existing wrappers around copy_from_user(). This will be used by the generic file system buffered read path. Signed-off-by: Dave Kleikamp Cc: Zach Brown --- fs/iov-iter.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/fs.h | 4 +++ 2 files changed, 84 insertions(+) diff --git a/fs/iov-iter.c b/fs/iov-iter.c index 563a6ba..0b2407e 100644 --- a/fs/iov-iter.c +++ b/fs/iov-iter.c @@ -6,6 +6,86 @@ #include #include +static size_t __iovec_copy_to_user(char *vaddr, const struct iovec *iov, + size_t base, size_t bytes, int atomic) +{ + size_t copied = 0, left = 0; + + while (bytes) { + char __user *buf = iov->iov_base + base; + int copy = min(bytes, iov->iov_len - base); + + base = 0; + if (atomic) + left = __copy_to_user_inatomic(buf, vaddr, copy); + else + left = copy_to_user(buf, vaddr, copy); + copied += copy; + bytes -= copy; + vaddr += copy; + iov++; + + if (unlikely(left)) + break; + } + return copied - left; +} + +/* + * Copy as much as we can into the page and return the number of bytes which + * 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, + struct iov_iter *i, unsigned long offset, size_t bytes) +{ + char *kaddr; + size_t copied; + + BUG_ON(!in_atomic()); + kaddr = kmap_atomic(page); + if (likely(i->nr_segs == 1)) { + int left; + char __user *buf = i->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, + 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(). + * 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) +{ + 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; + left = copy_to_user(buf, kaddr + offset, bytes); + copied = bytes - left; + } else { + copied = __iovec_copy_to_user(kaddr + offset, i->iov, + i->iov_offset, bytes, 0); + } + kunmap(page); + return copied; +} +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) { diff --git a/include/linux/fs.h b/include/linux/fs.h index 9818747..80f71df 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -296,6 +296,10 @@ struct iov_iter { 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_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, -- 1.8.3.4