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1efb473f BB |
1 | /* |
2 | * CDDL HEADER START | |
3 | * | |
4 | * The contents of this file are subject to the terms of the | |
5 | * Common Development and Distribution License (the "License"). | |
6 | * You may not use this file except in compliance with the License. | |
7 | * | |
8 | * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE | |
9 | * or http://www.opensolaris.org/os/licensing. | |
10 | * See the License for the specific language governing permissions | |
11 | * and limitations under the License. | |
12 | * | |
13 | * When distributing Covered Code, include this CDDL HEADER in each | |
14 | * file and include the License file at usr/src/OPENSOLARIS.LICENSE. | |
15 | * If applicable, add the following below this CDDL HEADER, with the | |
16 | * fields enclosed by brackets "[]" replaced with your own identifying | |
17 | * information: Portions Copyright [yyyy] [name of copyright owner] | |
18 | * | |
19 | * CDDL HEADER END | |
20 | */ | |
21 | /* | |
22 | * Copyright (c) 2011, Lawrence Livermore National Security, LLC. | |
23 | */ | |
24 | ||
25 | ||
26 | #include <sys/zfs_vfsops.h> | |
27 | #include <sys/zfs_vnops.h> | |
28 | #include <sys/zfs_znode.h> | |
29 | #include <sys/zpl.h> | |
30 | ||
31 | ||
126400a1 BB |
32 | static int |
33 | zpl_open(struct inode *ip, struct file *filp) | |
34 | { | |
35 | cred_t *cr; | |
36 | int error; | |
37 | ||
38 | cr = (cred_t *)get_current_cred(); | |
39 | error = -zfs_open(ip, filp->f_mode, filp->f_flags, cr); | |
40 | put_cred(cr); | |
41 | ASSERT3S(error, <=, 0); | |
42 | ||
43 | if (error) | |
44 | return (error); | |
45 | ||
46 | return generic_file_open(ip, filp); | |
47 | } | |
48 | ||
49 | static int | |
50 | zpl_release(struct inode *ip, struct file *filp) | |
51 | { | |
52 | cred_t *cr; | |
53 | int error; | |
54 | ||
55 | cr = (cred_t *)get_current_cred(); | |
56 | error = -zfs_close(ip, filp->f_flags, cr); | |
57 | put_cred(cr); | |
58 | ASSERT3S(error, <=, 0); | |
59 | ||
60 | return (error); | |
61 | } | |
62 | ||
1efb473f BB |
63 | static int |
64 | zpl_readdir(struct file *filp, void *dirent, filldir_t filldir) | |
65 | { | |
66 | struct dentry *dentry = filp->f_path.dentry; | |
67 | cred_t *cr; | |
68 | int error; | |
69 | ||
70 | cr = (cred_t *)get_current_cred(); | |
71 | error = -zfs_readdir(dentry->d_inode, dirent, filldir, | |
72 | &filp->f_pos, cr); | |
73 | put_cred(cr); | |
74 | ASSERT3S(error, <=, 0); | |
75 | ||
76 | return (error); | |
77 | } | |
78 | ||
7268e1be | 79 | ZPL_FSYNC_PROTO(zpl_fsync, filp, unused_dentry, datasync) |
1efb473f BB |
80 | { |
81 | cred_t *cr; | |
82 | int error; | |
83 | ||
84 | cr = (cred_t *)get_current_cred(); | |
85 | error = -zfs_fsync(filp->f_path.dentry->d_inode, datasync, cr); | |
86 | put_cred(cr); | |
87 | ASSERT3S(error, <=, 0); | |
88 | ||
89 | return (error); | |
90 | } | |
91 | ||
92 | ssize_t | |
93 | zpl_read_common(struct inode *ip, const char *buf, size_t len, loff_t pos, | |
94 | uio_seg_t segment, int flags, cred_t *cr) | |
95 | { | |
96 | int error; | |
97 | struct iovec iov; | |
98 | uio_t uio; | |
99 | ||
100 | iov.iov_base = (void *)buf; | |
101 | iov.iov_len = len; | |
102 | ||
103 | uio.uio_iov = &iov; | |
104 | uio.uio_resid = len; | |
105 | uio.uio_iovcnt = 1; | |
106 | uio.uio_loffset = pos; | |
107 | uio.uio_limit = MAXOFFSET_T; | |
108 | uio.uio_segflg = segment; | |
109 | ||
110 | error = -zfs_read(ip, &uio, flags, cr); | |
111 | if (error < 0) | |
112 | return (error); | |
113 | ||
114 | return (len - uio.uio_resid); | |
115 | } | |
116 | ||
117 | static ssize_t | |
118 | zpl_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos) | |
119 | { | |
120 | cred_t *cr; | |
121 | ssize_t read; | |
122 | ||
123 | cr = (cred_t *)get_current_cred(); | |
124 | read = zpl_read_common(filp->f_mapping->host, buf, len, *ppos, | |
125 | UIO_USERSPACE, filp->f_flags, cr); | |
126 | put_cred(cr); | |
127 | ||
128 | if (read < 0) | |
129 | return (read); | |
130 | ||
131 | *ppos += read; | |
132 | return (read); | |
133 | } | |
134 | ||
135 | ssize_t | |
136 | zpl_write_common(struct inode *ip, const char *buf, size_t len, loff_t pos, | |
137 | uio_seg_t segment, int flags, cred_t *cr) | |
138 | { | |
139 | int error; | |
140 | struct iovec iov; | |
141 | uio_t uio; | |
142 | ||
143 | iov.iov_base = (void *)buf; | |
144 | iov.iov_len = len; | |
145 | ||
146 | uio.uio_iov = &iov; | |
147 | uio.uio_resid = len, | |
148 | uio.uio_iovcnt = 1; | |
149 | uio.uio_loffset = pos; | |
150 | uio.uio_limit = MAXOFFSET_T; | |
151 | uio.uio_segflg = segment; | |
152 | ||
153 | error = -zfs_write(ip, &uio, flags, cr); | |
154 | if (error < 0) | |
155 | return (error); | |
156 | ||
157 | return (len - uio.uio_resid); | |
158 | } | |
159 | ||
160 | static ssize_t | |
161 | zpl_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos) | |
162 | { | |
163 | cred_t *cr; | |
164 | ssize_t wrote; | |
165 | ||
166 | cr = (cred_t *)get_current_cred(); | |
167 | wrote = zpl_write_common(filp->f_mapping->host, buf, len, *ppos, | |
168 | UIO_USERSPACE, filp->f_flags, cr); | |
169 | put_cred(cr); | |
170 | ||
171 | if (wrote < 0) | |
172 | return (wrote); | |
173 | ||
174 | *ppos += wrote; | |
175 | return (wrote); | |
176 | } | |
177 | ||
c0d35759 BB |
178 | /* |
179 | * It's worth taking a moment to describe how mmap is implemented | |
180 | * for zfs because it differs considerably from other Linux filesystems. | |
181 | * However, this issue is handled the same way under OpenSolaris. | |
182 | * | |
183 | * The issue is that by design zfs bypasses the Linux page cache and | |
184 | * leaves all caching up to the ARC. This has been shown to work | |
185 | * well for the common read(2)/write(2) case. However, mmap(2) | |
186 | * is problem because it relies on being tightly integrated with the | |
187 | * page cache. To handle this we cache mmap'ed files twice, once in | |
188 | * the ARC and a second time in the page cache. The code is careful | |
189 | * to keep both copies synchronized. | |
190 | * | |
191 | * When a file with an mmap'ed region is written to using write(2) | |
192 | * both the data in the ARC and existing pages in the page cache | |
193 | * are updated. For a read(2) data will be read first from the page | |
194 | * cache then the ARC if needed. Neither a write(2) or read(2) will | |
195 | * will ever result in new pages being added to the page cache. | |
196 | * | |
197 | * New pages are added to the page cache only via .readpage() which | |
198 | * is called when the vfs needs to read a page off disk to back the | |
199 | * virtual memory region. These pages may be modified without | |
200 | * notifying the ARC and will be written out periodically via | |
201 | * .writepage(). This will occur due to either a sync or the usual | |
202 | * page aging behavior. Note because a read(2) of a mmap'ed file | |
203 | * will always check the page cache first even when the ARC is out | |
204 | * of date correct data will still be returned. | |
205 | * | |
206 | * While this implementation ensures correct behavior it does have | |
207 | * have some drawbacks. The most obvious of which is that it | |
208 | * increases the required memory footprint when access mmap'ed | |
209 | * files. It also adds additional complexity to the code keeping | |
210 | * both caches synchronized. | |
211 | * | |
212 | * Longer term it may be possible to cleanly resolve this wart by | |
213 | * mapping page cache pages directly on to the ARC buffers. The | |
214 | * Linux address space operations are flexible enough to allow | |
215 | * selection of which pages back a particular index. The trick | |
216 | * would be working out the details of which subsystem is in | |
217 | * charge, the ARC, the page cache, or both. It may also prove | |
218 | * helpful to move the ARC buffers to a scatter-gather lists | |
219 | * rather than a vmalloc'ed region. | |
220 | */ | |
221 | static int | |
222 | zpl_mmap(struct file *filp, struct vm_area_struct *vma) | |
223 | { | |
224 | znode_t *zp = ITOZ(filp->f_mapping->host); | |
225 | int error; | |
226 | ||
227 | error = generic_file_mmap(filp, vma); | |
228 | if (error) | |
229 | return (error); | |
230 | ||
231 | mutex_enter(&zp->z_lock); | |
232 | zp->z_is_mapped = 1; | |
233 | mutex_exit(&zp->z_lock); | |
234 | ||
235 | return (error); | |
236 | } | |
237 | ||
238 | /* | |
239 | * Populate a page with data for the Linux page cache. This function is | |
240 | * only used to support mmap(2). There will be an identical copy of the | |
241 | * data in the ARC which is kept up to date via .write() and .writepage(). | |
242 | * | |
243 | * Current this function relies on zpl_read_common() and the O_DIRECT | |
244 | * flag to read in a page. This works but the more correct way is to | |
245 | * update zfs_fillpage() to be Linux friendly and use that interface. | |
246 | */ | |
247 | static int | |
248 | zpl_readpage(struct file *filp, struct page *pp) | |
249 | { | |
250 | struct inode *ip; | |
251 | loff_t off, i_size; | |
252 | size_t len, wrote; | |
253 | cred_t *cr; | |
254 | void *pb; | |
255 | int error = 0; | |
256 | ||
257 | ASSERT(PageLocked(pp)); | |
258 | ip = pp->mapping->host; | |
259 | off = page_offset(pp); | |
260 | i_size = i_size_read(ip); | |
261 | ASSERT3S(off, <, i_size); | |
262 | ||
263 | cr = (cred_t *)get_current_cred(); | |
264 | len = MIN(PAGE_CACHE_SIZE, i_size - off); | |
265 | ||
266 | pb = kmap(pp); | |
267 | ||
268 | /* O_DIRECT is passed to bypass the page cache and avoid deadlock. */ | |
269 | wrote = zpl_read_common(ip, pb, len, off, UIO_SYSSPACE, O_DIRECT, cr); | |
270 | if (wrote != len) | |
271 | error = -EIO; | |
272 | ||
273 | if (!error && (len < PAGE_CACHE_SIZE)) | |
274 | memset(pb + len, 0, PAGE_CACHE_SIZE - len); | |
275 | ||
276 | kunmap(pp); | |
277 | put_cred(cr); | |
278 | ||
279 | if (error) { | |
280 | SetPageError(pp); | |
281 | ClearPageUptodate(pp); | |
282 | } else { | |
283 | ClearPageError(pp); | |
284 | SetPageUptodate(pp); | |
285 | flush_dcache_page(pp); | |
286 | } | |
287 | ||
288 | unlock_page(pp); | |
289 | ||
290 | return (error); | |
291 | } | |
292 | ||
293 | /* | |
294 | * Write out dirty pages to the ARC, this function is only required to | |
295 | * support mmap(2). Mapped pages may be dirtied by memory operations | |
296 | * which never call .write(). These dirty pages are kept in sync with | |
297 | * the ARC buffers via this hook. | |
298 | * | |
299 | * Currently this function relies on zpl_write_common() and the O_DIRECT | |
300 | * flag to push out the page. This works but the more correct way is | |
301 | * to update zfs_putapage() to be Linux friendly and use that interface. | |
302 | */ | |
303 | static int | |
304 | zpl_writepage(struct page *pp, struct writeback_control *wbc) | |
305 | { | |
306 | struct inode *ip; | |
307 | loff_t off, i_size; | |
308 | size_t len, read; | |
309 | cred_t *cr; | |
310 | void *pb; | |
311 | int error = 0; | |
312 | ||
313 | ASSERT(PageLocked(pp)); | |
314 | ip = pp->mapping->host; | |
315 | off = page_offset(pp); | |
316 | i_size = i_size_read(ip); | |
317 | ||
318 | cr = (cred_t *)get_current_cred(); | |
319 | len = MIN(PAGE_CACHE_SIZE, i_size - off); | |
320 | ||
321 | pb = kmap(pp); | |
322 | ||
323 | /* O_DIRECT is passed to bypass the page cache and avoid deadlock. */ | |
324 | read = zpl_write_common(ip, pb, len, off, UIO_SYSSPACE, O_DIRECT, cr); | |
325 | if (read != len) | |
326 | error = -EIO; | |
327 | ||
328 | kunmap(pp); | |
329 | put_cred(cr); | |
330 | ||
331 | if (error) { | |
332 | SetPageError(pp); | |
333 | ClearPageUptodate(pp); | |
334 | } else { | |
335 | ClearPageError(pp); | |
336 | SetPageUptodate(pp); | |
337 | } | |
338 | ||
339 | unlock_page(pp); | |
340 | ||
341 | return (error); | |
342 | } | |
343 | ||
1efb473f | 344 | const struct address_space_operations zpl_address_space_operations = { |
1efb473f BB |
345 | .readpage = zpl_readpage, |
346 | .writepage = zpl_writepage, | |
1efb473f BB |
347 | }; |
348 | ||
349 | const struct file_operations zpl_file_operations = { | |
126400a1 BB |
350 | .open = zpl_open, |
351 | .release = zpl_release, | |
1efb473f | 352 | .llseek = generic_file_llseek, |
c0d35759 BB |
353 | .read = zpl_read, |
354 | .write = zpl_write, | |
1efb473f | 355 | .readdir = zpl_readdir, |
c0d35759 | 356 | .mmap = zpl_mmap, |
1efb473f | 357 | .fsync = zpl_fsync, |
1efb473f BB |
358 | }; |
359 | ||
360 | const struct file_operations zpl_dir_file_operations = { | |
361 | .llseek = generic_file_llseek, | |
362 | .read = generic_read_dir, | |
363 | .readdir = zpl_readdir, | |
364 | .fsync = zpl_fsync, | |
365 | }; |