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.
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.
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]
22 * Copyright (c) 2011, Lawrence Livermore National Security, LLC.
26 #include <sys/zfs_vfsops.h>
27 #include <sys/zfs_vnops.h>
28 #include <sys/zfs_znode.h>
33 zpl_open(struct inode *ip, struct file *filp)
39 error = -zfs_open(ip, filp->f_mode, filp->f_flags, cr);
41 ASSERT3S(error, <=, 0);
46 return generic_file_open(ip, filp);
50 zpl_release(struct inode *ip, struct file *filp)
56 error = -zfs_close(ip, filp->f_flags, cr);
58 ASSERT3S(error, <=, 0);
64 zpl_readdir(struct file *filp, void *dirent, filldir_t filldir)
66 struct dentry *dentry = filp->f_path.dentry;
71 error = -zfs_readdir(dentry->d_inode, dirent, filldir,
74 ASSERT3S(error, <=, 0);
79 #if defined(HAVE_FSYNC_WITH_DENTRY)
81 * Linux 2.6.x - 2.6.34 API,
82 * Through 2.6.34 the nfsd kernel server would pass a NULL 'file struct *'
83 * to the fops->fsync() hook. For this reason, we must be careful not to
84 * use filp unconditionally.
87 zpl_fsync(struct file *filp, struct dentry *dentry, int datasync)
93 error = -zfs_fsync(dentry->d_inode, datasync, cr);
95 ASSERT3S(error, <=, 0);
100 #elif defined(HAVE_FSYNC_WITHOUT_DENTRY)
102 * Linux 2.6.35 - 3.0 API,
103 * As of 2.6.35 the dentry argument to the fops->fsync() hook was deemed
104 * redundant. The dentry is still accessible via filp->f_path.dentry,
105 * and we are guaranteed that filp will never be NULL.
108 zpl_fsync(struct file *filp, int datasync)
110 struct inode *inode = filp->f_mapping->host;
115 error = -zfs_fsync(inode, datasync, cr);
117 ASSERT3S(error, <=, 0);
122 #elif defined(HAVE_FSYNC_RANGE)
124 * Linux 3.1 - 3.x API,
125 * As of 3.1 the responsibility to call filemap_write_and_wait_range() has
126 * been pushed down in to the .fsync() vfs hook. Additionally, the i_mutex
127 * lock is no longer held by the caller, for zfs we don't require the lock
128 * to be held so we don't acquire it.
131 zpl_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
133 struct inode *inode = filp->f_mapping->host;
137 error = filemap_write_and_wait_range(inode->i_mapping, start, end);
142 error = -zfs_fsync(inode, datasync, cr);
144 ASSERT3S(error, <=, 0);
149 #error "Unsupported fops->fsync() implementation"
153 zpl_read_common(struct inode *ip, const char *buf, size_t len, loff_t pos,
154 uio_seg_t segment, int flags, cred_t *cr)
160 iov.iov_base = (void *)buf;
166 uio.uio_loffset = pos;
167 uio.uio_limit = MAXOFFSET_T;
168 uio.uio_segflg = segment;
170 error = -zfs_read(ip, &uio, flags, cr);
174 return (len - uio.uio_resid);
178 zpl_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
184 read = zpl_read_common(filp->f_mapping->host, buf, len, *ppos,
185 UIO_USERSPACE, filp->f_flags, cr);
196 zpl_write_common(struct inode *ip, const char *buf, size_t len, loff_t pos,
197 uio_seg_t segment, int flags, cred_t *cr)
203 iov.iov_base = (void *)buf;
209 uio.uio_loffset = pos;
210 uio.uio_limit = MAXOFFSET_T;
211 uio.uio_segflg = segment;
213 error = -zfs_write(ip, &uio, flags, cr);
217 return (len - uio.uio_resid);
221 zpl_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
227 wrote = zpl_write_common(filp->f_mapping->host, buf, len, *ppos,
228 UIO_USERSPACE, filp->f_flags, cr);
239 * It's worth taking a moment to describe how mmap is implemented
240 * for zfs because it differs considerably from other Linux filesystems.
241 * However, this issue is handled the same way under OpenSolaris.
243 * The issue is that by design zfs bypasses the Linux page cache and
244 * leaves all caching up to the ARC. This has been shown to work
245 * well for the common read(2)/write(2) case. However, mmap(2)
246 * is problem because it relies on being tightly integrated with the
247 * page cache. To handle this we cache mmap'ed files twice, once in
248 * the ARC and a second time in the page cache. The code is careful
249 * to keep both copies synchronized.
251 * When a file with an mmap'ed region is written to using write(2)
252 * both the data in the ARC and existing pages in the page cache
253 * are updated. For a read(2) data will be read first from the page
254 * cache then the ARC if needed. Neither a write(2) or read(2) will
255 * will ever result in new pages being added to the page cache.
257 * New pages are added to the page cache only via .readpage() which
258 * is called when the vfs needs to read a page off disk to back the
259 * virtual memory region. These pages may be modified without
260 * notifying the ARC and will be written out periodically via
261 * .writepage(). This will occur due to either a sync or the usual
262 * page aging behavior. Note because a read(2) of a mmap'ed file
263 * will always check the page cache first even when the ARC is out
264 * of date correct data will still be returned.
266 * While this implementation ensures correct behavior it does have
267 * have some drawbacks. The most obvious of which is that it
268 * increases the required memory footprint when access mmap'ed
269 * files. It also adds additional complexity to the code keeping
270 * both caches synchronized.
272 * Longer term it may be possible to cleanly resolve this wart by
273 * mapping page cache pages directly on to the ARC buffers. The
274 * Linux address space operations are flexible enough to allow
275 * selection of which pages back a particular index. The trick
276 * would be working out the details of which subsystem is in
277 * charge, the ARC, the page cache, or both. It may also prove
278 * helpful to move the ARC buffers to a scatter-gather lists
279 * rather than a vmalloc'ed region.
282 zpl_mmap(struct file *filp, struct vm_area_struct *vma)
284 struct inode *ip = filp->f_mapping->host;
285 znode_t *zp = ITOZ(ip);
288 error = -zfs_map(ip, vma->vm_pgoff, (caddr_t *)vma->vm_start,
289 (size_t)(vma->vm_end - vma->vm_start), vma->vm_flags);
293 error = generic_file_mmap(filp, vma);
297 mutex_enter(&zp->z_lock);
299 mutex_exit(&zp->z_lock);
305 * Populate a page with data for the Linux page cache. This function is
306 * only used to support mmap(2). There will be an identical copy of the
307 * data in the ARC which is kept up to date via .write() and .writepage().
309 * Current this function relies on zpl_read_common() and the O_DIRECT
310 * flag to read in a page. This works but the more correct way is to
311 * update zfs_fillpage() to be Linux friendly and use that interface.
314 zpl_readpage(struct file *filp, struct page *pp)
320 ASSERT(PageLocked(pp));
321 ip = pp->mapping->host;
324 error = -zfs_getpage(ip, pl, 1);
328 ClearPageUptodate(pp);
332 flush_dcache_page(pp);
340 * Populate a set of pages with data for the Linux page cache. This
341 * function will only be called for read ahead and never for demand
342 * paging. For simplicity, the code relies on read_cache_pages() to
343 * correctly lock each page for IO and call zpl_readpage().
346 zpl_readpages(struct file *filp, struct address_space *mapping,
347 struct list_head *pages, unsigned nr_pages)
349 return (read_cache_pages(mapping, pages,
350 (filler_t *)zpl_readpage, filp));
354 zpl_putpage(struct page *pp, struct writeback_control *wbc, void *data)
356 struct address_space *mapping = data;
358 ASSERT(PageLocked(pp));
359 ASSERT(!PageWriteback(pp));
362 * Disable the normal reclaim path for zpl_putpage(). This
363 * ensures that all memory allocations under this call path
364 * will never enter direct reclaim. If this were to happen
365 * the VM might try to write out additional pages by calling
366 * zpl_putpage() again resulting in a deadlock.
368 if (current->flags & PF_MEMALLOC) {
369 (void) zfs_putpage(mapping->host, pp, wbc);
371 current->flags |= PF_MEMALLOC;
372 (void) zfs_putpage(mapping->host, pp, wbc);
373 current->flags &= ~PF_MEMALLOC;
380 zpl_writepages(struct address_space *mapping, struct writeback_control *wbc)
382 return write_cache_pages(mapping, wbc, zpl_putpage, mapping);
386 * Write out dirty pages to the ARC, this function is only required to
387 * support mmap(2). Mapped pages may be dirtied by memory operations
388 * which never call .write(). These dirty pages are kept in sync with
389 * the ARC buffers via this hook.
392 zpl_writepage(struct page *pp, struct writeback_control *wbc)
394 return zpl_putpage(pp, wbc, pp->mapping);
398 * The only flag combination which matches the behavior of zfs_space()
399 * is FALLOC_FL_PUNCH_HOLE. This flag was introduced in the 2.6.38 kernel.
402 zpl_fallocate_common(struct inode *ip, int mode, loff_t offset, loff_t len)
405 int error = -EOPNOTSUPP;
407 if (mode & FALLOC_FL_KEEP_SIZE)
408 return (-EOPNOTSUPP);
412 #ifdef FALLOC_FL_PUNCH_HOLE
413 if (mode & FALLOC_FL_PUNCH_HOLE) {
422 error = -zfs_space(ip, F_FREESP, &bf, FWRITE, offset, cr);
424 #endif /* FALLOC_FL_PUNCH_HOLE */
428 ASSERT3S(error, <=, 0);
432 #ifdef HAVE_FILE_FALLOCATE
434 zpl_fallocate(struct file *filp, int mode, loff_t offset, loff_t len)
436 return zpl_fallocate_common(filp->f_path.dentry->d_inode,
439 #endif /* HAVE_FILE_FALLOCATE */
441 const struct address_space_operations zpl_address_space_operations = {
442 .readpages = zpl_readpages,
443 .readpage = zpl_readpage,
444 .writepage = zpl_writepage,
445 .writepages = zpl_writepages,
448 const struct file_operations zpl_file_operations = {
450 .release = zpl_release,
451 .llseek = generic_file_llseek,
454 .readdir = zpl_readdir,
457 #ifdef HAVE_FILE_FALLOCATE
458 .fallocate = zpl_fallocate,
459 #endif /* HAVE_FILE_FALLOCATE */
462 const struct file_operations zpl_dir_file_operations = {
463 .llseek = generic_file_llseek,
464 .read = generic_read_dir,
465 .readdir = zpl_readdir,