1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext2/file.c
4 *
5 * Copyright (C) 1992, 1993, 1994, 1995
6 * Remy Card (card@masi.ibp.fr)
7 * Laboratoire MASI - Institut Blaise Pascal
8 * Universite Pierre et Marie Curie (Paris VI)
9 *
10 * from
11 *
12 * linux/fs/minix/file.c
13 *
14 * Copyright (C) 1991, 1992 Linus Torvalds
15 *
16 * ext2 fs regular file handling primitives
17 *
18 * 64-bit file support on 64-bit platforms by Jakub Jelinek
19 * (jj@sunsite.ms.mff.cuni.cz)
20 */
21
22#include <linux/time.h>
23#include <linux/pagemap.h>
24#include <linux/dax.h>
25#include <linux/quotaops.h>
26#include <linux/iomap.h>
27#include <linux/uio.h>
28#include <linux/buffer_head.h>
29#include "ext2.h"
30#include "xattr.h"
31#include "acl.h"
32#include "trace.h"
33
34#ifdef CONFIG_FS_DAX
35static ssize_t ext2_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
36{
37 struct inode *inode = iocb->ki_filp->f_mapping->host;
38 ssize_t ret;
39
40 if (!iov_iter_count(i: to))
41 return 0; /* skip atime */
42
43 inode_lock_shared(inode);
44 ret = dax_iomap_rw(iocb, iter: to, ops: &ext2_iomap_ops);
45 inode_unlock_shared(inode);
46
47 file_accessed(file: iocb->ki_filp);
48 return ret;
49}
50
51static ssize_t ext2_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
52{
53 struct file *file = iocb->ki_filp;
54 struct inode *inode = file->f_mapping->host;
55 ssize_t ret;
56
57 inode_lock(inode);
58 ret = generic_write_checks(iocb, from);
59 if (ret <= 0)
60 goto out_unlock;
61 ret = file_remove_privs(file);
62 if (ret)
63 goto out_unlock;
64 ret = file_update_time(file);
65 if (ret)
66 goto out_unlock;
67
68 ret = dax_iomap_rw(iocb, iter: from, ops: &ext2_iomap_ops);
69 if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
70 i_size_write(inode, i_size: iocb->ki_pos);
71 mark_inode_dirty(inode);
72 }
73
74out_unlock:
75 inode_unlock(inode);
76 if (ret > 0)
77 ret = generic_write_sync(iocb, count: ret);
78 return ret;
79}
80
81/*
82 * The lock ordering for ext2 DAX fault paths is:
83 *
84 * mmap_lock (MM)
85 * sb_start_pagefault (vfs, freeze)
86 * address_space->invalidate_lock
87 * address_space->i_mmap_rwsem or page_lock (mutually exclusive in DAX)
88 * ext2_inode_info->truncate_mutex
89 *
90 * The default page_lock and i_size verification done by non-DAX fault paths
91 * is sufficient because ext2 doesn't support hole punching.
92 */
93static vm_fault_t ext2_dax_fault(struct vm_fault *vmf)
94{
95 struct inode *inode = file_inode(f: vmf->vma->vm_file);
96 vm_fault_t ret;
97 bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
98 (vmf->vma->vm_flags & VM_SHARED);
99
100 if (write) {
101 sb_start_pagefault(sb: inode->i_sb);
102 file_update_time(file: vmf->vma->vm_file);
103 }
104 filemap_invalidate_lock_shared(mapping: inode->i_mapping);
105
106 ret = dax_iomap_fault(vmf, order: 0, NULL, NULL, ops: &ext2_iomap_ops);
107
108 filemap_invalidate_unlock_shared(mapping: inode->i_mapping);
109 if (write)
110 sb_end_pagefault(sb: inode->i_sb);
111 return ret;
112}
113
114static const struct vm_operations_struct ext2_dax_vm_ops = {
115 .fault = ext2_dax_fault,
116 /*
117 * .huge_fault is not supported for DAX because allocation in ext2
118 * cannot be reliably aligned to huge page sizes and so pmd faults
119 * will always fail and fail back to regular faults.
120 */
121 .page_mkwrite = ext2_dax_fault,
122 .pfn_mkwrite = ext2_dax_fault,
123};
124
125static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
126{
127 if (!IS_DAX(file_inode(file)))
128 return generic_file_mmap(file, vma);
129
130 file_accessed(file);
131 vma->vm_ops = &ext2_dax_vm_ops;
132 return 0;
133}
134#else
135#define ext2_file_mmap generic_file_mmap
136#endif
137
138/*
139 * Called when filp is released. This happens when all file descriptors
140 * for a single struct file are closed. Note that different open() calls
141 * for the same file yield different struct file structures.
142 */
143static int ext2_release_file (struct inode * inode, struct file * filp)
144{
145 if (filp->f_mode & FMODE_WRITE) {
146 mutex_lock(&EXT2_I(inode)->truncate_mutex);
147 ext2_discard_reservation(inode);
148 mutex_unlock(lock: &EXT2_I(inode)->truncate_mutex);
149 }
150 return 0;
151}
152
153int ext2_fsync(struct file *file, loff_t start, loff_t end, int datasync)
154{
155 int ret;
156 struct super_block *sb = file->f_mapping->host->i_sb;
157
158 ret = generic_buffers_fsync(file, start, end, datasync);
159 if (ret == -EIO)
160 /* We don't really know where the IO error happened... */
161 ext2_error(sb, __func__,
162 "detected IO error when writing metadata buffers");
163 return ret;
164}
165
166static ssize_t ext2_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
167{
168 struct file *file = iocb->ki_filp;
169 struct inode *inode = file->f_mapping->host;
170 ssize_t ret;
171
172 trace_ext2_dio_read_begin(iocb, iter: to, ret: 0);
173 inode_lock_shared(inode);
174 ret = iomap_dio_rw(iocb, iter: to, ops: &ext2_iomap_ops, NULL, dio_flags: 0, NULL, done_before: 0);
175 inode_unlock_shared(inode);
176 trace_ext2_dio_read_end(iocb, iter: to, ret);
177
178 return ret;
179}
180
181static int ext2_dio_write_end_io(struct kiocb *iocb, ssize_t size,
182 int error, unsigned int flags)
183{
184 loff_t pos = iocb->ki_pos;
185 struct inode *inode = file_inode(f: iocb->ki_filp);
186
187 if (error)
188 goto out;
189
190 /*
191 * If we are extending the file, we have to update i_size here before
192 * page cache gets invalidated in iomap_dio_rw(). This prevents racing
193 * buffered reads from zeroing out too much from page cache pages.
194 * Note that all extending writes always happens synchronously with
195 * inode lock held by ext2_dio_write_iter(). So it is safe to update
196 * inode size here for extending file writes.
197 */
198 pos += size;
199 if (pos > i_size_read(inode)) {
200 i_size_write(inode, i_size: pos);
201 mark_inode_dirty(inode);
202 }
203out:
204 trace_ext2_dio_write_endio(iocb, size, ret: error);
205 return error;
206}
207
208static const struct iomap_dio_ops ext2_dio_write_ops = {
209 .end_io = ext2_dio_write_end_io,
210};
211
212static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
213{
214 struct file *file = iocb->ki_filp;
215 struct inode *inode = file->f_mapping->host;
216 ssize_t ret;
217 unsigned int flags = 0;
218 unsigned long blocksize = inode->i_sb->s_blocksize;
219 loff_t offset = iocb->ki_pos;
220 loff_t count = iov_iter_count(i: from);
221 ssize_t status = 0;
222
223 trace_ext2_dio_write_begin(iocb, iter: from, ret: 0);
224 inode_lock(inode);
225 ret = generic_write_checks(iocb, from);
226 if (ret <= 0)
227 goto out_unlock;
228
229 ret = kiocb_modified(iocb);
230 if (ret)
231 goto out_unlock;
232
233 /* use IOMAP_DIO_FORCE_WAIT for unaligned or extending writes */
234 if (iocb->ki_pos + iov_iter_count(i: from) > i_size_read(inode) ||
235 (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(from), blocksize)))
236 flags |= IOMAP_DIO_FORCE_WAIT;
237
238 ret = iomap_dio_rw(iocb, iter: from, ops: &ext2_iomap_ops, dops: &ext2_dio_write_ops,
239 dio_flags: flags, NULL, done_before: 0);
240
241 /* ENOTBLK is magic return value for fallback to buffered-io */
242 if (ret == -ENOTBLK)
243 ret = 0;
244
245 if (ret < 0 && ret != -EIOCBQUEUED)
246 ext2_write_failed(mapping: inode->i_mapping, to: offset + count);
247
248 /* handle case for partial write and for fallback to buffered write */
249 if (ret >= 0 && iov_iter_count(i: from)) {
250 loff_t pos, endbyte;
251 int ret2;
252
253 iocb->ki_flags &= ~IOCB_DIRECT;
254 pos = iocb->ki_pos;
255 status = generic_perform_write(iocb, from);
256 if (unlikely(status < 0)) {
257 ret = status;
258 goto out_unlock;
259 }
260
261 iocb->ki_pos += status;
262 ret += status;
263 endbyte = pos + status - 1;
264 ret2 = filemap_write_and_wait_range(mapping: inode->i_mapping, lstart: pos,
265 lend: endbyte);
266 if (!ret2)
267 invalidate_mapping_pages(mapping: inode->i_mapping,
268 start: pos >> PAGE_SHIFT,
269 end: endbyte >> PAGE_SHIFT);
270 if (ret > 0)
271 generic_write_sync(iocb, count: ret);
272 }
273
274out_unlock:
275 inode_unlock(inode);
276 if (status)
277 trace_ext2_dio_write_buff_end(iocb, iter: from, ret: status);
278 trace_ext2_dio_write_end(iocb, iter: from, ret);
279 return ret;
280}
281
282static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
283{
284#ifdef CONFIG_FS_DAX
285 if (IS_DAX(iocb->ki_filp->f_mapping->host))
286 return ext2_dax_read_iter(iocb, to);
287#endif
288 if (iocb->ki_flags & IOCB_DIRECT)
289 return ext2_dio_read_iter(iocb, to);
290
291 return generic_file_read_iter(iocb, to);
292}
293
294static ssize_t ext2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
295{
296#ifdef CONFIG_FS_DAX
297 if (IS_DAX(iocb->ki_filp->f_mapping->host))
298 return ext2_dax_write_iter(iocb, from);
299#endif
300 if (iocb->ki_flags & IOCB_DIRECT)
301 return ext2_dio_write_iter(iocb, from);
302
303 return generic_file_write_iter(iocb, from);
304}
305
306const struct file_operations ext2_file_operations = {
307 .llseek = generic_file_llseek,
308 .read_iter = ext2_file_read_iter,
309 .write_iter = ext2_file_write_iter,
310 .unlocked_ioctl = ext2_ioctl,
311#ifdef CONFIG_COMPAT
312 .compat_ioctl = ext2_compat_ioctl,
313#endif
314 .mmap = ext2_file_mmap,
315 .open = dquot_file_open,
316 .release = ext2_release_file,
317 .fsync = ext2_fsync,
318 .get_unmapped_area = thp_get_unmapped_area,
319 .splice_read = filemap_splice_read,
320 .splice_write = iter_file_splice_write,
321};
322
323const struct inode_operations ext2_file_inode_operations = {
324 .listxattr = ext2_listxattr,
325 .getattr = ext2_getattr,
326 .setattr = ext2_setattr,
327 .get_inode_acl = ext2_get_acl,
328 .set_acl = ext2_set_acl,
329 .fiemap = ext2_fiemap,
330 .fileattr_get = ext2_fileattr_get,
331 .fileattr_set = ext2_fileattr_set,
332};
333

source code of linux/fs/ext2/file.c