cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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xfs_pnfs.c (8685B)


      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Copyright (c) 2014 Christoph Hellwig.
      4 */
      5#include "xfs.h"
      6#include "xfs_shared.h"
      7#include "xfs_format.h"
      8#include "xfs_log_format.h"
      9#include "xfs_trans_resv.h"
     10#include "xfs_mount.h"
     11#include "xfs_inode.h"
     12#include "xfs_trans.h"
     13#include "xfs_bmap.h"
     14#include "xfs_iomap.h"
     15#include "xfs_pnfs.h"
     16
     17/*
     18 * Ensure that we do not have any outstanding pNFS layouts that can be used by
     19 * clients to directly read from or write to this inode.  This must be called
     20 * before every operation that can remove blocks from the extent map.
     21 * Additionally we call it during the write operation, where aren't concerned
     22 * about exposing unallocated blocks but just want to provide basic
     23 * synchronization between a local writer and pNFS clients.  mmap writes would
     24 * also benefit from this sort of synchronization, but due to the tricky locking
     25 * rules in the page fault path we don't bother.
     26 */
     27int
     28xfs_break_leased_layouts(
     29	struct inode		*inode,
     30	uint			*iolock,
     31	bool			*did_unlock)
     32{
     33	struct xfs_inode	*ip = XFS_I(inode);
     34	int			error;
     35
     36	while ((error = break_layout(inode, false)) == -EWOULDBLOCK) {
     37		xfs_iunlock(ip, *iolock);
     38		*did_unlock = true;
     39		error = break_layout(inode, true);
     40		*iolock &= ~XFS_IOLOCK_SHARED;
     41		*iolock |= XFS_IOLOCK_EXCL;
     42		xfs_ilock(ip, *iolock);
     43	}
     44
     45	return error;
     46}
     47
     48/*
     49 * Get a unique ID including its location so that the client can identify
     50 * the exported device.
     51 */
     52int
     53xfs_fs_get_uuid(
     54	struct super_block	*sb,
     55	u8			*buf,
     56	u32			*len,
     57	u64			*offset)
     58{
     59	struct xfs_mount	*mp = XFS_M(sb);
     60
     61	xfs_notice_once(mp,
     62"Using experimental pNFS feature, use at your own risk!");
     63
     64	if (*len < sizeof(uuid_t))
     65		return -EINVAL;
     66
     67	memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
     68	*len = sizeof(uuid_t);
     69	*offset = offsetof(struct xfs_dsb, sb_uuid);
     70	return 0;
     71}
     72
     73/*
     74 * We cannot use file based VFS helpers such as file_modified() to update
     75 * inode state as we modify the data/metadata in the inode here. Hence we have
     76 * to open code the timestamp updates and SUID/SGID stripping. We also need
     77 * to set the inode prealloc flag to ensure that the extents we allocate are not
     78 * removed if the inode is reclaimed from memory before xfs_fs_block_commit()
     79 * is from the client to indicate that data has been written and the file size
     80 * can be extended.
     81 */
     82static int
     83xfs_fs_map_update_inode(
     84	struct xfs_inode	*ip)
     85{
     86	struct xfs_trans	*tp;
     87	int			error;
     88
     89	error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_writeid,
     90			0, 0, 0, &tp);
     91	if (error)
     92		return error;
     93
     94	xfs_ilock(ip, XFS_ILOCK_EXCL);
     95	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
     96
     97	VFS_I(ip)->i_mode &= ~S_ISUID;
     98	if (VFS_I(ip)->i_mode & S_IXGRP)
     99		VFS_I(ip)->i_mode &= ~S_ISGID;
    100	xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
    101	ip->i_diflags |= XFS_DIFLAG_PREALLOC;
    102
    103	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
    104	return xfs_trans_commit(tp);
    105}
    106
    107/*
    108 * Get a layout for the pNFS client.
    109 */
    110int
    111xfs_fs_map_blocks(
    112	struct inode		*inode,
    113	loff_t			offset,
    114	u64			length,
    115	struct iomap		*iomap,
    116	bool			write,
    117	u32			*device_generation)
    118{
    119	struct xfs_inode	*ip = XFS_I(inode);
    120	struct xfs_mount	*mp = ip->i_mount;
    121	struct xfs_bmbt_irec	imap;
    122	xfs_fileoff_t		offset_fsb, end_fsb;
    123	loff_t			limit;
    124	int			bmapi_flags = XFS_BMAPI_ENTIRE;
    125	int			nimaps = 1;
    126	uint			lock_flags;
    127	int			error = 0;
    128
    129	if (xfs_is_shutdown(mp))
    130		return -EIO;
    131
    132	/*
    133	 * We can't export inodes residing on the realtime device.  The realtime
    134	 * device doesn't have a UUID to identify it, so the client has no way
    135	 * to find it.
    136	 */
    137	if (XFS_IS_REALTIME_INODE(ip))
    138		return -ENXIO;
    139
    140	/*
    141	 * The pNFS block layout spec actually supports reflink like
    142	 * functionality, but the Linux pNFS server doesn't implement it yet.
    143	 */
    144	if (xfs_is_reflink_inode(ip))
    145		return -ENXIO;
    146
    147	/*
    148	 * Lock out any other I/O before we flush and invalidate the pagecache,
    149	 * and then hand out a layout to the remote system.  This is very
    150	 * similar to direct I/O, except that the synchronization is much more
    151	 * complicated.  See the comment near xfs_break_leased_layouts
    152	 * for a detailed explanation.
    153	 */
    154	xfs_ilock(ip, XFS_IOLOCK_EXCL);
    155
    156	error = -EINVAL;
    157	limit = mp->m_super->s_maxbytes;
    158	if (!write)
    159		limit = max(limit, round_up(i_size_read(inode),
    160				     inode->i_sb->s_blocksize));
    161	if (offset > limit)
    162		goto out_unlock;
    163	if (offset > limit - length)
    164		length = limit - offset;
    165
    166	error = filemap_write_and_wait(inode->i_mapping);
    167	if (error)
    168		goto out_unlock;
    169	error = invalidate_inode_pages2(inode->i_mapping);
    170	if (WARN_ON_ONCE(error))
    171		goto out_unlock;
    172
    173	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
    174	offset_fsb = XFS_B_TO_FSBT(mp, offset);
    175
    176	lock_flags = xfs_ilock_data_map_shared(ip);
    177	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
    178				&imap, &nimaps, bmapi_flags);
    179
    180	ASSERT(!nimaps || imap.br_startblock != DELAYSTARTBLOCK);
    181
    182	if (!error && write &&
    183	    (!nimaps || imap.br_startblock == HOLESTARTBLOCK)) {
    184		if (offset + length > XFS_ISIZE(ip))
    185			end_fsb = xfs_iomap_eof_align_last_fsb(ip, end_fsb);
    186		else if (nimaps && imap.br_startblock == HOLESTARTBLOCK)
    187			end_fsb = min(end_fsb, imap.br_startoff +
    188					       imap.br_blockcount);
    189		xfs_iunlock(ip, lock_flags);
    190
    191		error = xfs_iomap_write_direct(ip, offset_fsb,
    192				end_fsb - offset_fsb, 0, &imap);
    193		if (error)
    194			goto out_unlock;
    195
    196		/*
    197		 * Ensure the next transaction is committed synchronously so
    198		 * that the blocks allocated and handed out to the client are
    199		 * guaranteed to be present even after a server crash.
    200		 */
    201		error = xfs_fs_map_update_inode(ip);
    202		if (!error)
    203			error = xfs_log_force_inode(ip);
    204		if (error)
    205			goto out_unlock;
    206
    207	} else {
    208		xfs_iunlock(ip, lock_flags);
    209	}
    210	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
    211
    212	error = xfs_bmbt_to_iomap(ip, iomap, &imap, 0, 0);
    213	*device_generation = mp->m_generation;
    214	return error;
    215out_unlock:
    216	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
    217	return error;
    218}
    219
    220/*
    221 * Ensure the size update falls into a valid allocated block.
    222 */
    223static int
    224xfs_pnfs_validate_isize(
    225	struct xfs_inode	*ip,
    226	xfs_off_t		isize)
    227{
    228	struct xfs_bmbt_irec	imap;
    229	int			nimaps = 1;
    230	int			error = 0;
    231
    232	xfs_ilock(ip, XFS_ILOCK_SHARED);
    233	error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
    234				&imap, &nimaps, 0);
    235	xfs_iunlock(ip, XFS_ILOCK_SHARED);
    236	if (error)
    237		return error;
    238
    239	if (imap.br_startblock == HOLESTARTBLOCK ||
    240	    imap.br_startblock == DELAYSTARTBLOCK ||
    241	    imap.br_state == XFS_EXT_UNWRITTEN)
    242		return -EIO;
    243	return 0;
    244}
    245
    246/*
    247 * Make sure the blocks described by maps are stable on disk.  This includes
    248 * converting any unwritten extents, flushing the disk cache and updating the
    249 * time stamps.
    250 *
    251 * Note that we rely on the caller to always send us a timestamp update so that
    252 * we always commit a transaction here.  If that stops being true we will have
    253 * to manually flush the cache here similar to what the fsync code path does
    254 * for datasyncs on files that have no dirty metadata.
    255 */
    256int
    257xfs_fs_commit_blocks(
    258	struct inode		*inode,
    259	struct iomap		*maps,
    260	int			nr_maps,
    261	struct iattr		*iattr)
    262{
    263	struct xfs_inode	*ip = XFS_I(inode);
    264	struct xfs_mount	*mp = ip->i_mount;
    265	struct xfs_trans	*tp;
    266	bool			update_isize = false;
    267	int			error, i;
    268	loff_t			size;
    269
    270	ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
    271
    272	xfs_ilock(ip, XFS_IOLOCK_EXCL);
    273
    274	size = i_size_read(inode);
    275	if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
    276		update_isize = true;
    277		size = iattr->ia_size;
    278	}
    279
    280	for (i = 0; i < nr_maps; i++) {
    281		u64 start, length, end;
    282
    283		start = maps[i].offset;
    284		if (start > size)
    285			continue;
    286
    287		end = start + maps[i].length;
    288		if (end > size)
    289			end = size;
    290
    291		length = end - start;
    292		if (!length)
    293			continue;
    294
    295		/*
    296		 * Make sure reads through the pagecache see the new data.
    297		 */
    298		error = invalidate_inode_pages2_range(inode->i_mapping,
    299					start >> PAGE_SHIFT,
    300					(end - 1) >> PAGE_SHIFT);
    301		WARN_ON_ONCE(error);
    302
    303		error = xfs_iomap_write_unwritten(ip, start, length, false);
    304		if (error)
    305			goto out_drop_iolock;
    306	}
    307
    308	if (update_isize) {
    309		error = xfs_pnfs_validate_isize(ip, size);
    310		if (error)
    311			goto out_drop_iolock;
    312	}
    313
    314	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
    315	if (error)
    316		goto out_drop_iolock;
    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	ASSERT(!(iattr->ia_valid & (ATTR_UID | ATTR_GID)));
    323	setattr_copy(&init_user_ns, inode, iattr);
    324	if (update_isize) {
    325		i_size_write(inode, iattr->ia_size);
    326		ip->i_disk_size = iattr->ia_size;
    327	}
    328
    329	xfs_trans_set_sync(tp);
    330	error = xfs_trans_commit(tp);
    331
    332out_drop_iolock:
    333	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
    334	return error;
    335}