1/*
  2 * Copyright (c) 2014 Christoph Hellwig.
  3 */
  4#include "xfs.h"
  5#include "xfs_format.h"
  6#include "xfs_log_format.h"
  7#include "xfs_trans_resv.h"
  8#include "xfs_sb.h"
  9#include "xfs_mount.h"
 10#include "xfs_inode.h"
 11#include "xfs_trans.h"
 12#include "xfs_log.h"
 13#include "xfs_bmap.h"
 14#include "xfs_bmap_util.h"
 15#include "xfs_error.h"
 16#include "xfs_iomap.h"
 17#include "xfs_shared.h"
 18#include "xfs_bit.h"
 19#include "xfs_pnfs.h"
 20
 21/*
 22 * Ensure that we do not have any outstanding pNFS layouts that can be used by
 23 * clients to directly read from or write to this inode.  This must be called
 24 * before every operation that can remove blocks from the extent map.
 25 * Additionally we call it during the write operation, where aren't concerned
 26 * about exposing unallocated blocks but just want to provide basic
 27 * synchronization between a local writer and pNFS clients.  mmap writes would
 28 * also benefit from this sort of synchronization, but due to the tricky locking
 29 * rules in the page fault path we don't bother.
 30 */
 31int
 32xfs_break_layouts(
 33	struct inode		*inode,
 34	uint			*iolock,
 35	bool			with_imutex)
 36{
 37	struct xfs_inode	*ip = XFS_I(inode);
 38	int			error;
 39
 40	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL));
 41
 42	while ((error = break_layout(inode, false) == -EWOULDBLOCK)) {
 43		xfs_iunlock(ip, *iolock);
 44		if (with_imutex && (*iolock & XFS_IOLOCK_EXCL))
 45			inode_unlock(inode);
 46		error = break_layout(inode, true);
 47		*iolock = XFS_IOLOCK_EXCL;
 48		if (with_imutex)
 49			inode_lock(inode);
 50		xfs_ilock(ip, *iolock);
 51	}
 52
 53	return error;
 54}
 55
 56/*
 57 * Get a unique ID including its location so that the client can identify
 58 * the exported device.
 59 */
 60int
 61xfs_fs_get_uuid(
 62	struct super_block	*sb,
 63	u8			*buf,
 64	u32			*len,
 65	u64			*offset)
 66{
 67	struct xfs_mount	*mp = XFS_M(sb);
 68
 69	printk_once(KERN_NOTICE
 70"XFS (%s): using experimental pNFS feature, use at your own risk!\n",
 71		mp->m_fsname);
 72
 73	if (*len < sizeof(uuid_t))
 74		return -EINVAL;
 75
 76	memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
 77	*len = sizeof(uuid_t);
 78	*offset = offsetof(struct xfs_dsb, sb_uuid);
 79	return 0;
 80}
 81
 82static void
 83xfs_bmbt_to_iomap(
 84	struct xfs_inode	*ip,
 85	struct iomap		*iomap,
 86	struct xfs_bmbt_irec	*imap)
 87{
 88	struct xfs_mount	*mp = ip->i_mount;
 89
 90	if (imap->br_startblock == HOLESTARTBLOCK) {
 91		iomap->blkno = IOMAP_NULL_BLOCK;
 92		iomap->type = IOMAP_HOLE;
 93	} else if (imap->br_startblock == DELAYSTARTBLOCK) {
 94		iomap->blkno = IOMAP_NULL_BLOCK;
 95		iomap->type = IOMAP_DELALLOC;
 96	} else {
 97		iomap->blkno =
 98			XFS_FSB_TO_DADDR(ip->i_mount, imap->br_startblock);
 99		if (imap->br_state == XFS_EXT_UNWRITTEN)
100			iomap->type = IOMAP_UNWRITTEN;
101		else
102			iomap->type = IOMAP_MAPPED;
103	}
104	iomap->offset = XFS_FSB_TO_B(mp, imap->br_startoff);
105	iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
106}
107
108/*
109 * Get a layout for the pNFS client.
110 */
111int
112xfs_fs_map_blocks(
113	struct inode		*inode,
114	loff_t			offset,
115	u64			length,
116	struct iomap		*iomap,
117	bool			write,
118	u32			*device_generation)
119{
120	struct xfs_inode	*ip = XFS_I(inode);
121	struct xfs_mount	*mp = ip->i_mount;
122	struct xfs_bmbt_irec	imap;
123	xfs_fileoff_t		offset_fsb, end_fsb;
124	loff_t			limit;
125	int			bmapi_flags = XFS_BMAPI_ENTIRE;
126	int			nimaps = 1;
127	uint			lock_flags;
128	int			error = 0;
129
130	if (XFS_FORCED_SHUTDOWN(mp))
131		return -EIO;
132
133	/*
134	 * We can't export inodes residing on the realtime device.  The realtime
135	 * device doesn't have a UUID to identify it, so the client has no way
136	 * to find it.
137	 */
138	if (XFS_IS_REALTIME_INODE(ip))
139		return -ENXIO;
140
141	/*
142	 * Lock out any other I/O before we flush and invalidate the pagecache,
143	 * and then hand out a layout to the remote system.  This is very
144	 * similar to direct I/O, except that the synchronization is much more
145	 * complicated.  See the comment near xfs_break_layouts for a detailed
146	 * explanation.
147	 */
148	xfs_ilock(ip, XFS_IOLOCK_EXCL);
149
150	error = -EINVAL;
151	limit = mp->m_super->s_maxbytes;
152	if (!write)
153		limit = max(limit, round_up(i_size_read(inode),
154				     inode->i_sb->s_blocksize));
155	if (offset > limit)
156		goto out_unlock;
157	if (offset > limit - length)
158		length = limit - offset;
159
160	error = filemap_write_and_wait(inode->i_mapping);
161	if (error)
162		goto out_unlock;
163	error = invalidate_inode_pages2(inode->i_mapping);
164	if (WARN_ON_ONCE(error))
165		return error;
166
167	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
168	offset_fsb = XFS_B_TO_FSBT(mp, offset);
169
170	lock_flags = xfs_ilock_data_map_shared(ip);
171	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
172				&imap, &nimaps, bmapi_flags);
173	xfs_iunlock(ip, lock_flags);
174
175	if (error)
176		goto out_unlock;
177
178	if (write) {
179		enum xfs_prealloc_flags	flags = 0;
180
181		ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
182
183		if (!nimaps || imap.br_startblock == HOLESTARTBLOCK) {
184			/*
185			 * xfs_iomap_write_direct() expects to take ownership of
186			 * the shared ilock.
187			 */
188			xfs_ilock(ip, XFS_ILOCK_SHARED);
189			error = xfs_iomap_write_direct(ip, offset, length,
190						       &imap, nimaps);
191			if (error)
192				goto out_unlock;
193
194			/*
195			 * Ensure the next transaction is committed
196			 * synchronously so that the blocks allocated and
197			 * handed out to the client are guaranteed to be
198			 * present even after a server crash.
199			 */
200			flags |= XFS_PREALLOC_SET | XFS_PREALLOC_SYNC;
201		}
202
203		error = xfs_update_prealloc_flags(ip, flags);
204		if (error)
205			goto out_unlock;
206	}
207	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
208
209	xfs_bmbt_to_iomap(ip, iomap, &imap);
210	*device_generation = mp->m_generation;
211	return error;
212out_unlock:
213	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
214	return error;
215}
216
217/*
218 * Ensure the size update falls into a valid allocated block.
219 */
220static int
221xfs_pnfs_validate_isize(
222	struct xfs_inode	*ip,
223	xfs_off_t		isize)
224{
225	struct xfs_bmbt_irec	imap;
226	int			nimaps = 1;
227	int			error = 0;
228
229	xfs_ilock(ip, XFS_ILOCK_SHARED);
230	error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
231				&imap, &nimaps, 0);
232	xfs_iunlock(ip, XFS_ILOCK_SHARED);
233	if (error)
234		return error;
235
236	if (imap.br_startblock == HOLESTARTBLOCK ||
237	    imap.br_startblock == DELAYSTARTBLOCK ||
238	    imap.br_state == XFS_EXT_UNWRITTEN)
239		return -EIO;
240	return 0;
241}
242
243/*
244 * Make sure the blocks described by maps are stable on disk.  This includes
245 * converting any unwritten extents, flushing the disk cache and updating the
246 * time stamps.
247 *
248 * Note that we rely on the caller to always send us a timestamp update so that
249 * we always commit a transaction here.  If that stops being true we will have
250 * to manually flush the cache here similar to what the fsync code path does
251 * for datasyncs on files that have no dirty metadata.
252 */
253int
254xfs_fs_commit_blocks(
255	struct inode		*inode,
256	struct iomap		*maps,
257	int			nr_maps,
258	struct iattr		*iattr)
259{
260	struct xfs_inode	*ip = XFS_I(inode);
261	struct xfs_mount	*mp = ip->i_mount;
262	struct xfs_trans	*tp;
263	bool			update_isize = false;
264	int			error, i;
265	loff_t			size;
266
267	ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
268
269	xfs_ilock(ip, XFS_IOLOCK_EXCL);
270
271	size = i_size_read(inode);
272	if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
273		update_isize = true;
274		size = iattr->ia_size;
275	}
276
277	for (i = 0; i < nr_maps; i++) {
278		u64 start, length, end;
279
280		start = maps[i].offset;
281		if (start > size)
282			continue;
283
284		end = start + maps[i].length;
285		if (end > size)
286			end = size;
287
288		length = end - start;
289		if (!length)
290			continue;
291	
292		/*
293		 * Make sure reads through the pagecache see the new data.
294		 */
295		error = invalidate_inode_pages2_range(inode->i_mapping,
296					start >> PAGE_SHIFT,
297					(end - 1) >> PAGE_SHIFT);
298		WARN_ON_ONCE(error);
299
300		error = xfs_iomap_write_unwritten(ip, start, length);
301		if (error)
302			goto out_drop_iolock;
303	}
304
305	if (update_isize) {
306		error = xfs_pnfs_validate_isize(ip, size);
307		if (error)
308			goto out_drop_iolock;
309	}
310
311	tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_NOT_SIZE);
312	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ichange, 0, 0);
313	if (error) {
314		xfs_trans_cancel(tp);
315		goto out_drop_iolock;
316	}
317
318	xfs_ilock(ip, XFS_ILOCK_EXCL);
319	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
320	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
321
322	xfs_setattr_time(ip, iattr);
323	if (update_isize) {
324		i_size_write(inode, iattr->ia_size);
325		ip->i_d.di_size = iattr->ia_size;
326	}
327
328	xfs_trans_set_sync(tp);
329	error = xfs_trans_commit(tp);
330
331out_drop_iolock:
332	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
333	return error;
334}