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f79e2abb AM |
1 | /* |
2 | * High-level sync()-related operations | |
3 | */ | |
4 | ||
5 | #include <linux/kernel.h> | |
6 | #include <linux/file.h> | |
7 | #include <linux/fs.h> | |
8 | #include <linux/module.h> | |
9 | #include <linux/writeback.h> | |
10 | #include <linux/syscalls.h> | |
11 | #include <linux/linkage.h> | |
12 | #include <linux/pagemap.h> | |
13 | ||
14 | #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \ | |
15 | SYNC_FILE_RANGE_WAIT_AFTER) | |
16 | ||
17 | /* | |
18 | * sys_sync_file_range() permits finely controlled syncing over a segment of | |
19 | * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is | |
20 | * zero then sys_sync_file_range() will operate from offset out to EOF. | |
21 | * | |
22 | * The flag bits are: | |
23 | * | |
24 | * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range | |
25 | * before performing the write. | |
26 | * | |
27 | * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the | |
28 | * range which are not presently under writeback. | |
29 | * | |
30 | * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range | |
31 | * after performing the write. | |
32 | * | |
33 | * Useful combinations of the flag bits are: | |
34 | * | |
35 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages | |
36 | * in the range which were dirty on entry to sys_sync_file_range() are placed | |
37 | * under writeout. This is a start-write-for-data-integrity operation. | |
38 | * | |
39 | * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which | |
40 | * are not presently under writeout. This is an asynchronous flush-to-disk | |
41 | * operation. Not suitable for data integrity operations. | |
42 | * | |
43 | * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for | |
44 | * completion of writeout of all pages in the range. This will be used after an | |
45 | * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait | |
46 | * for that operation to complete and to return the result. | |
47 | * | |
48 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: | |
49 | * a traditional sync() operation. This is a write-for-data-integrity operation | |
50 | * which will ensure that all pages in the range which were dirty on entry to | |
51 | * sys_sync_file_range() are committed to disk. | |
52 | * | |
53 | * | |
54 | * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any | |
55 | * I/O errors or ENOSPC conditions and will return those to the caller, after | |
56 | * clearing the EIO and ENOSPC flags in the address_space. | |
57 | * | |
58 | * It should be noted that none of these operations write out the file's | |
59 | * metadata. So unless the application is strictly performing overwrites of | |
60 | * already-instantiated disk blocks, there are no guarantees here that the data | |
61 | * will be available after a crash. | |
62 | */ | |
63 | asmlinkage long sys_sync_file_range(int fd, loff_t offset, loff_t nbytes, | |
5246d050 | 64 | unsigned int flags) |
f79e2abb AM |
65 | { |
66 | int ret; | |
67 | struct file *file; | |
68 | loff_t endbyte; /* inclusive */ | |
69 | int fput_needed; | |
70 | umode_t i_mode; | |
71 | ||
72 | ret = -EINVAL; | |
73 | if (flags & ~VALID_FLAGS) | |
74 | goto out; | |
75 | ||
76 | endbyte = offset + nbytes; | |
77 | ||
78 | if ((s64)offset < 0) | |
79 | goto out; | |
80 | if ((s64)endbyte < 0) | |
81 | goto out; | |
82 | if (endbyte < offset) | |
83 | goto out; | |
84 | ||
85 | if (sizeof(pgoff_t) == 4) { | |
86 | if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { | |
87 | /* | |
88 | * The range starts outside a 32 bit machine's | |
89 | * pagecache addressing capabilities. Let it "succeed" | |
90 | */ | |
91 | ret = 0; | |
92 | goto out; | |
93 | } | |
94 | if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { | |
95 | /* | |
96 | * Out to EOF | |
97 | */ | |
98 | nbytes = 0; | |
99 | } | |
100 | } | |
101 | ||
102 | if (nbytes == 0) | |
103 | endbyte = -1; | |
104 | else | |
105 | endbyte--; /* inclusive */ | |
106 | ||
107 | ret = -EBADF; | |
108 | file = fget_light(fd, &fput_needed); | |
109 | if (!file) | |
110 | goto out; | |
111 | ||
112 | i_mode = file->f_dentry->d_inode->i_mode; | |
113 | ret = -ESPIPE; | |
114 | if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && | |
115 | !S_ISLNK(i_mode)) | |
116 | goto out_put; | |
117 | ||
118 | ret = do_sync_file_range(file, offset, endbyte, flags); | |
119 | out_put: | |
120 | fput_light(file, fput_needed); | |
121 | out: | |
122 | return ret; | |
123 | } | |
124 | ||
125 | /* | |
126 | * `endbyte' is inclusive | |
127 | */ | |
128 | int do_sync_file_range(struct file *file, loff_t offset, loff_t endbyte, | |
5246d050 | 129 | unsigned int flags) |
f79e2abb AM |
130 | { |
131 | int ret; | |
132 | struct address_space *mapping; | |
133 | ||
134 | mapping = file->f_mapping; | |
135 | if (!mapping) { | |
136 | ret = -EINVAL; | |
137 | goto out; | |
138 | } | |
139 | ||
140 | ret = 0; | |
141 | if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { | |
142 | ret = wait_on_page_writeback_range(mapping, | |
143 | offset >> PAGE_CACHE_SHIFT, | |
144 | endbyte >> PAGE_CACHE_SHIFT); | |
145 | if (ret < 0) | |
146 | goto out; | |
147 | } | |
148 | ||
149 | if (flags & SYNC_FILE_RANGE_WRITE) { | |
150 | ret = __filemap_fdatawrite_range(mapping, offset, endbyte, | |
151 | WB_SYNC_NONE); | |
152 | if (ret < 0) | |
153 | goto out; | |
154 | } | |
155 | ||
156 | if (flags & SYNC_FILE_RANGE_WAIT_AFTER) { | |
157 | ret = wait_on_page_writeback_range(mapping, | |
158 | offset >> PAGE_CACHE_SHIFT, | |
159 | endbyte >> PAGE_CACHE_SHIFT); | |
160 | } | |
161 | out: | |
162 | return ret; | |
163 | } | |
164 | EXPORT_SYMBOL_GPL(do_sync_file_range); |