1 #include <linux/ceph/ceph_debug.h>
3 #include <linux/module.h>
4 #include <linux/sched.h>
5 #include <linux/slab.h>
6 #include <linux/file.h>
7 #include <linux/namei.h>
8 #include <linux/writeback.h>
11 #include "mds_client.h"
14 * Ceph file operations
16 * Implement basic open/close functionality, and implement
19 * We implement three modes of file I/O:
20 * - buffered uses the generic_file_aio_{read,write} helpers
22 * - synchronous is used when there is multi-client read/write
23 * sharing, avoids the page cache, and synchronously waits for an
26 * - direct io takes the variant of the sync path that references
27 * user pages directly.
29 * fsync() flushes and waits on dirty pages, but just queues metadata
30 * for writeback: since the MDS can recover size and mtime there is no
31 * need to wait for MDS acknowledgement.
36 * Prepare an open request. Preallocate ceph_cap to avoid an
37 * inopportune ENOMEM later.
39 static struct ceph_mds_request *
40 prepare_open_request(struct super_block *sb, int flags, int create_mode)
42 struct ceph_fs_client *fsc = ceph_sb_to_client(sb);
43 struct ceph_mds_client *mdsc = fsc->mdsc;
44 struct ceph_mds_request *req;
45 int want_auth = USE_ANY_MDS;
46 int op = (flags & O_CREAT) ? CEPH_MDS_OP_CREATE : CEPH_MDS_OP_OPEN;
48 if (flags & (O_WRONLY|O_RDWR|O_CREAT|O_TRUNC))
49 want_auth = USE_AUTH_MDS;
51 req = ceph_mdsc_create_request(mdsc, op, want_auth);
54 req->r_fmode = ceph_flags_to_mode(flags);
55 req->r_args.open.flags = cpu_to_le32(flags);
56 req->r_args.open.mode = cpu_to_le32(create_mode);
57 req->r_args.open.preferred = cpu_to_le32(-1);
63 * initialize private struct file data.
64 * if we fail, clean up by dropping fmode reference on the ceph_inode
66 static int ceph_init_file(struct inode *inode, struct file *file, int fmode)
68 struct ceph_file_info *cf;
71 switch (inode->i_mode & S_IFMT) {
74 dout("init_file %p %p 0%o (regular)\n", inode, file,
76 cf = kmem_cache_alloc(ceph_file_cachep, GFP_NOFS | __GFP_ZERO);
78 ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
83 file->private_data = cf;
84 BUG_ON(inode->i_fop->release != ceph_release);
88 dout("init_file %p %p 0%o (symlink)\n", inode, file,
90 ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
94 dout("init_file %p %p 0%o (special)\n", inode, file,
97 * we need to drop the open ref now, since we don't
98 * have .release set to ceph_release.
100 ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
101 BUG_ON(inode->i_fop->release == ceph_release);
103 /* call the proper open fop */
104 ret = inode->i_fop->open(inode, file);
110 * If the filp already has private_data, that means the file was
111 * already opened by intent during lookup, and we do nothing.
113 * If we already have the requisite capabilities, we can satisfy
114 * the open request locally (no need to request new caps from the
115 * MDS). We do, however, need to inform the MDS (asynchronously)
116 * if our wanted caps set expands.
118 int ceph_open(struct inode *inode, struct file *file)
120 struct ceph_inode_info *ci = ceph_inode(inode);
121 struct ceph_fs_client *fsc = ceph_sb_to_client(inode->i_sb);
122 struct ceph_mds_client *mdsc = fsc->mdsc;
123 struct ceph_mds_request *req;
124 struct ceph_file_info *cf = file->private_data;
125 struct inode *parent_inode = file->f_dentry->d_parent->d_inode;
127 int flags, fmode, wanted;
130 dout("open file %p is already opened\n", file);
134 /* filter out O_CREAT|O_EXCL; vfs did that already. yuck. */
135 flags = file->f_flags & ~(O_CREAT|O_EXCL);
136 if (S_ISDIR(inode->i_mode))
137 flags = O_DIRECTORY; /* mds likes to know */
139 dout("open inode %p ino %llx.%llx file %p flags %d (%d)\n", inode,
140 ceph_vinop(inode), file, flags, file->f_flags);
141 fmode = ceph_flags_to_mode(flags);
142 wanted = ceph_caps_for_mode(fmode);
144 /* snapped files are read-only */
145 if (ceph_snap(inode) != CEPH_NOSNAP && (file->f_mode & FMODE_WRITE))
148 /* trivially open snapdir */
149 if (ceph_snap(inode) == CEPH_SNAPDIR) {
150 spin_lock(&inode->i_lock);
151 __ceph_get_fmode(ci, fmode);
152 spin_unlock(&inode->i_lock);
153 return ceph_init_file(inode, file, fmode);
157 * No need to block if we have caps on the auth MDS (for
158 * write) or any MDS (for read). Update wanted set
161 spin_lock(&inode->i_lock);
162 if (__ceph_is_any_real_caps(ci) &&
163 (((fmode & CEPH_FILE_MODE_WR) == 0) || ci->i_auth_cap)) {
164 int mds_wanted = __ceph_caps_mds_wanted(ci);
165 int issued = __ceph_caps_issued(ci, NULL);
167 dout("open %p fmode %d want %s issued %s using existing\n",
168 inode, fmode, ceph_cap_string(wanted),
169 ceph_cap_string(issued));
170 __ceph_get_fmode(ci, fmode);
171 spin_unlock(&inode->i_lock);
174 if ((issued & wanted) != wanted &&
175 (mds_wanted & wanted) != wanted &&
176 ceph_snap(inode) != CEPH_SNAPDIR)
177 ceph_check_caps(ci, 0, NULL);
179 return ceph_init_file(inode, file, fmode);
180 } else if (ceph_snap(inode) != CEPH_NOSNAP &&
181 (ci->i_snap_caps & wanted) == wanted) {
182 __ceph_get_fmode(ci, fmode);
183 spin_unlock(&inode->i_lock);
184 return ceph_init_file(inode, file, fmode);
186 spin_unlock(&inode->i_lock);
188 dout("open fmode %d wants %s\n", fmode, ceph_cap_string(wanted));
189 req = prepare_open_request(inode->i_sb, flags, 0);
194 req->r_inode = inode;
197 err = ceph_mdsc_do_request(mdsc, parent_inode, req);
199 err = ceph_init_file(inode, file, req->r_fmode);
200 ceph_mdsc_put_request(req);
201 dout("open result=%d on %llx.%llx\n", err, ceph_vinop(inode));
208 * Do a lookup + open with a single request.
210 * If this succeeds, but some subsequent check in the vfs
211 * may_open() fails, the struct *file gets cleaned up (i.e.
212 * ceph_release gets called). So fear not!
216 * path_lookup_open -> LOOKUP_OPEN
217 * path_lookup_create -> LOOKUP_OPEN|LOOKUP_CREATE
219 struct dentry *ceph_lookup_open(struct inode *dir, struct dentry *dentry,
220 struct nameidata *nd, int mode,
223 struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb);
224 struct ceph_mds_client *mdsc = fsc->mdsc;
225 struct file *file = nd->intent.open.file;
226 struct inode *parent_inode = get_dentry_parent_inode(file->f_dentry);
227 struct ceph_mds_request *req;
229 int flags = nd->intent.open.flags - 1; /* silly vfs! */
231 dout("ceph_lookup_open dentry %p '%.*s' flags %d mode 0%o\n",
232 dentry, dentry->d_name.len, dentry->d_name.name, flags, mode);
235 req = prepare_open_request(dir->i_sb, flags, mode);
237 return ERR_CAST(req);
238 req->r_dentry = dget(dentry);
240 if (flags & O_CREAT) {
241 req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
242 req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
244 req->r_locked_dir = dir; /* caller holds dir->i_mutex */
245 err = ceph_mdsc_do_request(mdsc, parent_inode, req);
246 dentry = ceph_finish_lookup(req, dentry, err);
247 if (!err && (flags & O_CREAT) && !req->r_reply_info.head->is_dentry)
248 err = ceph_handle_notrace_create(dir, dentry);
250 err = ceph_init_file(req->r_dentry->d_inode, file,
252 ceph_mdsc_put_request(req);
253 dout("ceph_lookup_open result=%p\n", dentry);
257 int ceph_release(struct inode *inode, struct file *file)
259 struct ceph_inode_info *ci = ceph_inode(inode);
260 struct ceph_file_info *cf = file->private_data;
262 dout("release inode %p file %p\n", inode, file);
263 ceph_put_fmode(ci, cf->fmode);
264 if (cf->last_readdir)
265 ceph_mdsc_put_request(cf->last_readdir);
266 kfree(cf->last_name);
269 kmem_cache_free(ceph_file_cachep, cf);
271 /* wake up anyone waiting for caps on this inode */
272 wake_up_all(&ci->i_cap_wq);
277 * Read a range of bytes striped over one or more objects. Iterate over
278 * objects we stripe over. (That's not atomic, but good enough for now.)
280 * If we get a short result from the OSD, check against i_size; we need to
281 * only return a short read to the caller if we hit EOF.
283 static int striped_read(struct inode *inode,
285 struct page **pages, int num_pages,
286 int *checkeof, bool o_direct,
287 unsigned long buf_align)
289 struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
290 struct ceph_inode_info *ci = ceph_inode(inode);
292 int io_align, page_align;
293 int page_off = off & ~PAGE_CACHE_MASK; /* first byte's offset in page */
294 int left, pages_left;
296 struct page **page_pos;
298 bool hit_stripe, was_short;
301 * we may need to do multiple reads. not atomic, unfortunately.
306 pages_left = num_pages;
308 io_align = off & ~PAGE_MASK;
312 page_align = (pos - io_align + buf_align) & ~PAGE_MASK;
314 page_align = pos & ~PAGE_MASK;
316 ret = ceph_osdc_readpages(&fsc->client->osdc, ceph_vino(inode),
317 &ci->i_layout, pos, &this_len,
320 page_pos, pages_left, page_align);
321 hit_stripe = this_len < left;
322 was_short = ret >= 0 && ret < this_len;
325 dout("striped_read %llu~%u (read %u) got %d%s%s\n", pos, left, read,
326 ret, hit_stripe ? " HITSTRIPE" : "", was_short ? " SHORT" : "");
330 ((pos & ~PAGE_CACHE_MASK) + ret) >> PAGE_CACHE_SHIFT;
332 if (read < pos - off) {
333 dout(" zero gap %llu to %llu\n", off + read, pos);
334 ceph_zero_page_vector_range(page_off + read,
335 pos - off - read, pages);
340 page_pos += didpages;
341 pages_left -= didpages;
344 if (left && hit_stripe)
349 /* did we bounce off eof? */
350 if (pos + left > inode->i_size)
353 /* zero trailing bytes (inside i_size) */
354 if (left > 0 && pos < inode->i_size) {
355 if (pos + left > inode->i_size)
356 left = inode->i_size - pos;
358 dout("zero tail %d\n", left);
359 ceph_zero_page_vector_range(page_off + read, left,
367 dout("striped_read returns %d\n", ret);
372 * Completely synchronous read and write methods. Direct from __user
373 * buffer to osd, or directly to user pages (if O_DIRECT).
375 * If the read spans object boundary, just do multiple reads.
377 static ssize_t ceph_sync_read(struct file *file, char __user *data,
378 unsigned len, loff_t *poff, int *checkeof)
380 struct inode *inode = file->f_dentry->d_inode;
385 dout("sync_read on file %p %llu~%u %s\n", file, off, len,
386 (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");
388 if (file->f_flags & O_DIRECT) {
389 num_pages = calc_pages_for((unsigned long)data, len);
390 pages = ceph_get_direct_page_vector(data, num_pages, true);
392 num_pages = calc_pages_for(off, len);
393 pages = ceph_alloc_page_vector(num_pages, GFP_NOFS);
396 return PTR_ERR(pages);
399 * flush any page cache pages in this range. this
400 * will make concurrent normal and sync io slow,
401 * but it will at least behave sensibly when they are
404 ret = filemap_write_and_wait(inode->i_mapping);
408 ret = striped_read(inode, off, len, pages, num_pages, checkeof,
409 file->f_flags & O_DIRECT,
410 (unsigned long)data & ~PAGE_MASK);
412 if (ret >= 0 && (file->f_flags & O_DIRECT) == 0)
413 ret = ceph_copy_page_vector_to_user(pages, data, off, ret);
418 if (file->f_flags & O_DIRECT)
419 ceph_put_page_vector(pages, num_pages, true);
421 ceph_release_page_vector(pages, num_pages);
422 dout("sync_read result %d\n", ret);
427 * Write commit callback, called if we requested both an ACK and
428 * ONDISK commit reply from the OSD.
430 static void sync_write_commit(struct ceph_osd_request *req,
431 struct ceph_msg *msg)
433 struct ceph_inode_info *ci = ceph_inode(req->r_inode);
435 dout("sync_write_commit %p tid %llu\n", req, req->r_tid);
436 spin_lock(&ci->i_unsafe_lock);
437 list_del_init(&req->r_unsafe_item);
438 spin_unlock(&ci->i_unsafe_lock);
439 ceph_put_cap_refs(ci, CEPH_CAP_FILE_WR);
443 * Synchronous write, straight from __user pointer or user pages (if
446 * If write spans object boundary, just do multiple writes. (For a
447 * correct atomic write, we should e.g. take write locks on all
448 * objects, rollback on failure, etc.)
450 static ssize_t ceph_sync_write(struct file *file, const char __user *data,
451 size_t left, loff_t *offset)
453 struct inode *inode = file->f_dentry->d_inode;
454 struct ceph_inode_info *ci = ceph_inode(inode);
455 struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
456 struct ceph_osd_request *req;
459 long long unsigned pos;
465 int page_align, io_align;
466 unsigned long buf_align;
468 struct timespec mtime = CURRENT_TIME;
470 if (ceph_snap(file->f_dentry->d_inode) != CEPH_NOSNAP)
473 dout("sync_write on file %p %lld~%u %s\n", file, *offset,
474 (unsigned)left, (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");
476 if (file->f_flags & O_APPEND)
477 pos = i_size_read(inode);
481 io_align = pos & ~PAGE_MASK;
482 buf_align = (unsigned long)data & ~PAGE_MASK;
484 ret = filemap_write_and_wait_range(inode->i_mapping, pos, pos + left);
488 ret = invalidate_inode_pages2_range(inode->i_mapping,
489 pos >> PAGE_CACHE_SHIFT,
490 (pos + left) >> PAGE_CACHE_SHIFT);
492 dout("invalidate_inode_pages2_range returned %d\n", ret);
494 flags = CEPH_OSD_FLAG_ORDERSNAP |
495 CEPH_OSD_FLAG_ONDISK |
497 if ((file->f_flags & (O_SYNC|O_DIRECT)) == 0)
498 flags |= CEPH_OSD_FLAG_ACK;
503 * we may need to do multiple writes here if we span an object
504 * boundary. this isn't atomic, unfortunately. :(
508 if (file->f_flags & O_DIRECT) {
509 /* write from beginning of first page, regardless of
511 page_align = (pos - io_align + buf_align) & ~PAGE_MASK;
512 num_pages = calc_pages_for((unsigned long)data, len);
514 page_align = pos & ~PAGE_MASK;
515 num_pages = calc_pages_for(pos, len);
517 req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
518 ceph_vino(inode), pos, &len,
519 CEPH_OSD_OP_WRITE, flags,
520 ci->i_snap_realm->cached_context,
522 ci->i_truncate_seq, ci->i_truncate_size,
523 &mtime, false, 2, page_align);
527 if (file->f_flags & O_DIRECT) {
528 pages = ceph_get_direct_page_vector(data, num_pages, false);
530 ret = PTR_ERR(pages);
535 * throw out any page cache pages in this range. this
538 truncate_inode_pages_range(inode->i_mapping, pos,
539 (pos+len) | (PAGE_CACHE_SIZE-1));
541 pages = ceph_alloc_page_vector(num_pages, GFP_NOFS);
543 ret = PTR_ERR(pages);
546 ret = ceph_copy_user_to_page_vector(pages, data, pos, len);
548 ceph_release_page_vector(pages, num_pages);
552 if ((file->f_flags & O_SYNC) == 0) {
553 /* get a second commit callback */
554 req->r_safe_callback = sync_write_commit;
555 req->r_own_pages = 1;
558 req->r_pages = pages;
559 req->r_num_pages = num_pages;
560 req->r_inode = inode;
562 ret = ceph_osdc_start_request(&fsc->client->osdc, req, false);
564 if (req->r_safe_callback) {
566 * Add to inode unsafe list only after we
567 * start_request so that a tid has been assigned.
569 spin_lock(&ci->i_unsafe_lock);
570 list_add_tail(&req->r_unsafe_item,
571 &ci->i_unsafe_writes);
572 spin_unlock(&ci->i_unsafe_lock);
573 ceph_get_cap_refs(ci, CEPH_CAP_FILE_WR);
576 ret = ceph_osdc_wait_request(&fsc->client->osdc, req);
577 if (ret < 0 && req->r_safe_callback) {
578 spin_lock(&ci->i_unsafe_lock);
579 list_del_init(&req->r_unsafe_item);
580 spin_unlock(&ci->i_unsafe_lock);
581 ceph_put_cap_refs(ci, CEPH_CAP_FILE_WR);
585 if (file->f_flags & O_DIRECT)
586 ceph_put_page_vector(pages, num_pages, false);
587 else if (file->f_flags & O_SYNC)
588 ceph_release_page_vector(pages, num_pages);
591 ceph_osdc_put_request(req);
601 if (pos > i_size_read(inode))
602 check_caps = ceph_inode_set_size(inode, pos);
604 ceph_check_caps(ceph_inode(inode), CHECK_CAPS_AUTHONLY,
611 * Wrap generic_file_aio_read with checks for cap bits on the inode.
612 * Atomically grab references, so that those bits are not released
613 * back to the MDS mid-read.
615 * Hmm, the sync read case isn't actually async... should it be?
617 static ssize_t ceph_aio_read(struct kiocb *iocb, const struct iovec *iov,
618 unsigned long nr_segs, loff_t pos)
620 struct file *filp = iocb->ki_filp;
621 struct ceph_file_info *fi = filp->private_data;
622 loff_t *ppos = &iocb->ki_pos;
623 size_t len = iov->iov_len;
624 struct inode *inode = filp->f_dentry->d_inode;
625 struct ceph_inode_info *ci = ceph_inode(inode);
626 void __user *base = iov->iov_base;
629 int checkeof = 0, read = 0;
631 dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p\n",
632 inode, ceph_vinop(inode), pos, (unsigned)len, inode);
634 __ceph_do_pending_vmtruncate(inode);
635 if (fi->fmode & CEPH_FILE_MODE_LAZY)
636 want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;
638 want = CEPH_CAP_FILE_CACHE;
639 ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, want, &got, -1);
642 dout("aio_read %p %llx.%llx %llu~%u got cap refs on %s\n",
643 inode, ceph_vinop(inode), pos, (unsigned)len,
644 ceph_cap_string(got));
646 if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 ||
647 (iocb->ki_filp->f_flags & O_DIRECT) ||
648 (inode->i_sb->s_flags & MS_SYNCHRONOUS))
649 /* hmm, this isn't really async... */
650 ret = ceph_sync_read(filp, base, len, ppos, &checkeof);
652 ret = generic_file_aio_read(iocb, iov, nr_segs, pos);
655 dout("aio_read %p %llx.%llx dropping cap refs on %s = %d\n",
656 inode, ceph_vinop(inode), ceph_cap_string(got), (int)ret);
657 ceph_put_cap_refs(ci, got);
659 if (checkeof && ret >= 0) {
660 int statret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE);
662 /* hit EOF or hole? */
663 if (statret == 0 && *ppos < inode->i_size) {
664 dout("aio_read sync_read hit hole, ppos %lld < size %lld, reading more\n", *ppos, inode->i_size);
679 * Take cap references to avoid releasing caps to MDS mid-write.
681 * If we are synchronous, and write with an old snap context, the OSD
682 * may return EOLDSNAPC. In that case, retry the write.. _after_
683 * dropping our cap refs and allowing the pending snap to logically
684 * complete _before_ this write occurs.
686 * If we are near ENOSPC, write synchronously.
688 static ssize_t ceph_aio_write(struct kiocb *iocb, const struct iovec *iov,
689 unsigned long nr_segs, loff_t pos)
691 struct file *file = iocb->ki_filp;
692 struct ceph_file_info *fi = file->private_data;
693 struct inode *inode = file->f_dentry->d_inode;
694 struct ceph_inode_info *ci = ceph_inode(inode);
695 struct ceph_osd_client *osdc =
696 &ceph_sb_to_client(inode->i_sb)->client->osdc;
697 loff_t endoff = pos + iov->iov_len;
701 if (ceph_snap(inode) != CEPH_NOSNAP)
705 if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL))
707 __ceph_do_pending_vmtruncate(inode);
708 dout("aio_write %p %llx.%llx %llu~%u getting caps. i_size %llu\n",
709 inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
711 if (fi->fmode & CEPH_FILE_MODE_LAZY)
712 want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
714 want = CEPH_CAP_FILE_BUFFER;
715 ret = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, &got, endoff);
719 dout("aio_write %p %llx.%llx %llu~%u got cap refs on %s\n",
720 inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
721 ceph_cap_string(got));
723 if ((got & (CEPH_CAP_FILE_BUFFER|CEPH_CAP_FILE_LAZYIO)) == 0 ||
724 (iocb->ki_filp->f_flags & O_DIRECT) ||
725 (inode->i_sb->s_flags & MS_SYNCHRONOUS)) {
726 ret = ceph_sync_write(file, iov->iov_base, iov->iov_len,
729 ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
731 if ((ret >= 0 || ret == -EIOCBQUEUED) &&
732 ((file->f_flags & O_SYNC) || IS_SYNC(file->f_mapping->host)
733 || ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_NEARFULL))) {
734 err = vfs_fsync_range(file, pos, pos + ret - 1, 1);
741 spin_lock(&inode->i_lock);
742 dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR);
743 spin_unlock(&inode->i_lock);
745 __mark_inode_dirty(inode, dirty);
749 dout("aio_write %p %llx.%llx %llu~%u dropping cap refs on %s\n",
750 inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
751 ceph_cap_string(got));
752 ceph_put_cap_refs(ci, got);
754 if (ret == -EOLDSNAPC) {
755 dout("aio_write %p %llx.%llx %llu~%u got EOLDSNAPC, retrying\n",
756 inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len);
764 * llseek. be sure to verify file size on SEEK_END.
766 static loff_t ceph_llseek(struct file *file, loff_t offset, int origin)
768 struct inode *inode = file->f_mapping->host;
771 mutex_lock(&inode->i_mutex);
772 __ceph_do_pending_vmtruncate(inode);
775 ret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE);
780 offset += inode->i_size;
784 * Here we special-case the lseek(fd, 0, SEEK_CUR)
785 * position-querying operation. Avoid rewriting the "same"
786 * f_pos value back to the file because a concurrent read(),
787 * write() or lseek() might have altered it
790 offset = file->f_pos;
793 offset += file->f_pos;
797 if (offset < 0 || offset > inode->i_sb->s_maxbytes) {
802 /* Special lock needed here? */
803 if (offset != file->f_pos) {
804 file->f_pos = offset;
809 mutex_unlock(&inode->i_mutex);
813 const struct file_operations ceph_file_fops = {
815 .release = ceph_release,
816 .llseek = ceph_llseek,
817 .read = do_sync_read,
818 .write = do_sync_write,
819 .aio_read = ceph_aio_read,
820 .aio_write = ceph_aio_write,
825 .splice_read = generic_file_splice_read,
826 .splice_write = generic_file_splice_write,
827 .unlocked_ioctl = ceph_ioctl,
828 .compat_ioctl = ceph_ioctl,