Carsten Otte | ceffc07 | 2005-06-23 22:05:25 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/mm/filemap.h |
| 3 | * |
| 4 | * Copyright (C) 1994-1999 Linus Torvalds |
| 5 | */ |
| 6 | |
| 7 | #ifndef __FILEMAP_H |
| 8 | #define __FILEMAP_H |
| 9 | |
| 10 | #include <linux/types.h> |
| 11 | #include <linux/fs.h> |
| 12 | #include <linux/mm.h> |
| 13 | #include <linux/highmem.h> |
| 14 | #include <linux/uio.h> |
| 15 | #include <linux/config.h> |
Hiro Yoshioka | c22ce14 | 2006-06-23 02:04:16 -0700 | [diff] [blame] | 16 | #include <linux/uaccess.h> |
Carsten Otte | ceffc07 | 2005-06-23 22:05:25 -0700 | [diff] [blame] | 17 | |
Carsten Otte | eb6fe0c | 2005-06-23 22:05:28 -0700 | [diff] [blame] | 18 | size_t |
NeilBrown | 01408c4 | 2006-06-25 05:47:58 -0700 | [diff] [blame] | 19 | __filemap_copy_from_user_iovec_inatomic(char *vaddr, |
| 20 | const struct iovec *iov, |
| 21 | size_t base, |
| 22 | size_t bytes); |
Carsten Otte | ceffc07 | 2005-06-23 22:05:25 -0700 | [diff] [blame] | 23 | |
| 24 | /* |
| 25 | * Copy as much as we can into the page and return the number of bytes which |
| 26 | * were sucessfully copied. If a fault is encountered then clear the page |
| 27 | * out to (offset+bytes) and return the number of bytes which were copied. |
NeilBrown | 01408c4 | 2006-06-25 05:47:58 -0700 | [diff] [blame] | 28 | * |
| 29 | * NOTE: For this to work reliably we really want copy_from_user_inatomic_nocache |
| 30 | * to *NOT* zero any tail of the buffer that it failed to copy. If it does, |
| 31 | * and if the following non-atomic copy succeeds, then there is a small window |
| 32 | * where the target page contains neither the data before the write, nor the |
| 33 | * data after the write (it contains zero). A read at this time will see |
| 34 | * data that is inconsistent with any ordering of the read and the write. |
| 35 | * (This has been detected in practice). |
Carsten Otte | ceffc07 | 2005-06-23 22:05:25 -0700 | [diff] [blame] | 36 | */ |
| 37 | static inline size_t |
| 38 | filemap_copy_from_user(struct page *page, unsigned long offset, |
| 39 | const char __user *buf, unsigned bytes) |
| 40 | { |
| 41 | char *kaddr; |
| 42 | int left; |
| 43 | |
| 44 | kaddr = kmap_atomic(page, KM_USER0); |
Hiro Yoshioka | c22ce14 | 2006-06-23 02:04:16 -0700 | [diff] [blame] | 45 | left = __copy_from_user_inatomic_nocache(kaddr + offset, buf, bytes); |
Carsten Otte | ceffc07 | 2005-06-23 22:05:25 -0700 | [diff] [blame] | 46 | kunmap_atomic(kaddr, KM_USER0); |
| 47 | |
| 48 | if (left != 0) { |
| 49 | /* Do it the slow way */ |
| 50 | kaddr = kmap(page); |
Hiro Yoshioka | c22ce14 | 2006-06-23 02:04:16 -0700 | [diff] [blame] | 51 | left = __copy_from_user_nocache(kaddr + offset, buf, bytes); |
Carsten Otte | ceffc07 | 2005-06-23 22:05:25 -0700 | [diff] [blame] | 52 | kunmap(page); |
| 53 | } |
| 54 | return bytes - left; |
| 55 | } |
| 56 | |
| 57 | /* |
| 58 | * This has the same sideeffects and return value as filemap_copy_from_user(). |
| 59 | * The difference is that on a fault we need to memset the remainder of the |
| 60 | * page (out to offset+bytes), to emulate filemap_copy_from_user()'s |
| 61 | * single-segment behaviour. |
| 62 | */ |
| 63 | static inline size_t |
| 64 | filemap_copy_from_user_iovec(struct page *page, unsigned long offset, |
| 65 | const struct iovec *iov, size_t base, size_t bytes) |
| 66 | { |
| 67 | char *kaddr; |
| 68 | size_t copied; |
| 69 | |
| 70 | kaddr = kmap_atomic(page, KM_USER0); |
NeilBrown | 01408c4 | 2006-06-25 05:47:58 -0700 | [diff] [blame] | 71 | copied = __filemap_copy_from_user_iovec_inatomic(kaddr + offset, iov, |
| 72 | base, bytes); |
Carsten Otte | ceffc07 | 2005-06-23 22:05:25 -0700 | [diff] [blame] | 73 | kunmap_atomic(kaddr, KM_USER0); |
| 74 | if (copied != bytes) { |
| 75 | kaddr = kmap(page); |
NeilBrown | 01408c4 | 2006-06-25 05:47:58 -0700 | [diff] [blame] | 76 | copied = __filemap_copy_from_user_iovec_inatomic(kaddr + offset, iov, |
| 77 | base, bytes); |
| 78 | if (bytes - copied) |
| 79 | memset(kaddr + offset + copied, 0, bytes - copied); |
Carsten Otte | ceffc07 | 2005-06-23 22:05:25 -0700 | [diff] [blame] | 80 | kunmap(page); |
| 81 | } |
| 82 | return copied; |
| 83 | } |
| 84 | |
| 85 | static inline void |
| 86 | filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes) |
| 87 | { |
| 88 | const struct iovec *iov = *iovp; |
| 89 | size_t base = *basep; |
| 90 | |
| 91 | while (bytes) { |
| 92 | int copy = min(bytes, iov->iov_len - base); |
| 93 | |
| 94 | bytes -= copy; |
| 95 | base += copy; |
| 96 | if (iov->iov_len == base) { |
| 97 | iov++; |
| 98 | base = 0; |
| 99 | } |
| 100 | } |
| 101 | *iovp = iov; |
| 102 | *basep = base; |
| 103 | } |
| 104 | #endif |