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![Christian Brauner](/assets/img/avatar_default.png)
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b
("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
337 lines
8.5 KiB
C
337 lines
8.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2014 Christoph Hellwig.
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*/
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#include "xfs.h"
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#include "xfs_shared.h"
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#include "xfs_format.h"
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#include "xfs_log_format.h"
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#include "xfs_trans_resv.h"
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#include "xfs_mount.h"
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#include "xfs_inode.h"
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#include "xfs_trans.h"
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#include "xfs_bmap.h"
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#include "xfs_iomap.h"
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#include "xfs_pnfs.h"
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/*
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* Ensure that we do not have any outstanding pNFS layouts that can be used by
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* clients to directly read from or write to this inode. This must be called
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* before every operation that can remove blocks from the extent map.
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* Additionally we call it during the write operation, where aren't concerned
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* about exposing unallocated blocks but just want to provide basic
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* synchronization between a local writer and pNFS clients. mmap writes would
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* also benefit from this sort of synchronization, but due to the tricky locking
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* rules in the page fault path we don't bother.
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*/
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int
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xfs_break_leased_layouts(
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struct inode *inode,
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uint *iolock,
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bool *did_unlock)
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{
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struct xfs_inode *ip = XFS_I(inode);
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int error;
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while ((error = break_layout(inode, false)) == -EWOULDBLOCK) {
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xfs_iunlock(ip, *iolock);
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*did_unlock = true;
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error = break_layout(inode, true);
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*iolock &= ~XFS_IOLOCK_SHARED;
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*iolock |= XFS_IOLOCK_EXCL;
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xfs_ilock(ip, *iolock);
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}
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return error;
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}
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/*
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* Get a unique ID including its location so that the client can identify
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* the exported device.
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*/
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int
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xfs_fs_get_uuid(
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struct super_block *sb,
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u8 *buf,
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u32 *len,
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u64 *offset)
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{
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struct xfs_mount *mp = XFS_M(sb);
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xfs_notice_once(mp,
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"Using experimental pNFS feature, use at your own risk!");
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if (*len < sizeof(uuid_t))
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return -EINVAL;
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memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
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*len = sizeof(uuid_t);
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*offset = offsetof(struct xfs_dsb, sb_uuid);
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return 0;
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}
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/*
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* We cannot use file based VFS helpers such as file_modified() to update
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* inode state as we modify the data/metadata in the inode here. Hence we have
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* to open code the timestamp updates and SUID/SGID stripping. We also need
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* to set the inode prealloc flag to ensure that the extents we allocate are not
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* removed if the inode is reclaimed from memory before xfs_fs_block_commit()
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* is from the client to indicate that data has been written and the file size
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* can be extended.
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*/
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static int
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xfs_fs_map_update_inode(
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struct xfs_inode *ip)
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{
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struct xfs_trans *tp;
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int error;
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error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_writeid,
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0, 0, 0, &tp);
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if (error)
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return error;
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xfs_ilock(ip, XFS_ILOCK_EXCL);
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xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
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VFS_I(ip)->i_mode &= ~S_ISUID;
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if (VFS_I(ip)->i_mode & S_IXGRP)
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VFS_I(ip)->i_mode &= ~S_ISGID;
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xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
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ip->i_diflags |= XFS_DIFLAG_PREALLOC;
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xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
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return xfs_trans_commit(tp);
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}
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/*
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* Get a layout for the pNFS client.
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*/
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int
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xfs_fs_map_blocks(
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struct inode *inode,
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loff_t offset,
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u64 length,
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struct iomap *iomap,
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bool write,
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u32 *device_generation)
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{
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struct xfs_inode *ip = XFS_I(inode);
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struct xfs_mount *mp = ip->i_mount;
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struct xfs_bmbt_irec imap;
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xfs_fileoff_t offset_fsb, end_fsb;
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loff_t limit;
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int bmapi_flags = XFS_BMAPI_ENTIRE;
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int nimaps = 1;
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uint lock_flags;
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int error = 0;
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u64 seq;
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if (xfs_is_shutdown(mp))
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return -EIO;
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/*
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* We can't export inodes residing on the realtime device. The realtime
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* device doesn't have a UUID to identify it, so the client has no way
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* to find it.
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*/
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if (XFS_IS_REALTIME_INODE(ip))
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return -ENXIO;
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/*
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* The pNFS block layout spec actually supports reflink like
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* functionality, but the Linux pNFS server doesn't implement it yet.
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*/
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if (xfs_is_reflink_inode(ip))
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return -ENXIO;
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/*
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* Lock out any other I/O before we flush and invalidate the pagecache,
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* and then hand out a layout to the remote system. This is very
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* similar to direct I/O, except that the synchronization is much more
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* complicated. See the comment near xfs_break_leased_layouts
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* for a detailed explanation.
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*/
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xfs_ilock(ip, XFS_IOLOCK_EXCL);
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error = -EINVAL;
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limit = mp->m_super->s_maxbytes;
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if (!write)
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limit = max(limit, round_up(i_size_read(inode),
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inode->i_sb->s_blocksize));
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if (offset > limit)
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goto out_unlock;
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if (offset > limit - length)
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length = limit - offset;
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error = filemap_write_and_wait(inode->i_mapping);
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if (error)
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goto out_unlock;
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error = invalidate_inode_pages2(inode->i_mapping);
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if (WARN_ON_ONCE(error))
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goto out_unlock;
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end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
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offset_fsb = XFS_B_TO_FSBT(mp, offset);
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lock_flags = xfs_ilock_data_map_shared(ip);
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error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
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&imap, &nimaps, bmapi_flags);
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seq = xfs_iomap_inode_sequence(ip, 0);
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ASSERT(!nimaps || imap.br_startblock != DELAYSTARTBLOCK);
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if (!error && write &&
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(!nimaps || imap.br_startblock == HOLESTARTBLOCK)) {
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if (offset + length > XFS_ISIZE(ip))
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end_fsb = xfs_iomap_eof_align_last_fsb(ip, end_fsb);
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else if (nimaps && imap.br_startblock == HOLESTARTBLOCK)
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end_fsb = min(end_fsb, imap.br_startoff +
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imap.br_blockcount);
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xfs_iunlock(ip, lock_flags);
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error = xfs_iomap_write_direct(ip, offset_fsb,
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end_fsb - offset_fsb, 0, &imap, &seq);
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if (error)
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goto out_unlock;
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/*
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* Ensure the next transaction is committed synchronously so
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* that the blocks allocated and handed out to the client are
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* guaranteed to be present even after a server crash.
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*/
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error = xfs_fs_map_update_inode(ip);
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if (!error)
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error = xfs_log_force_inode(ip);
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if (error)
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goto out_unlock;
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} else {
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xfs_iunlock(ip, lock_flags);
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}
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xfs_iunlock(ip, XFS_IOLOCK_EXCL);
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error = xfs_bmbt_to_iomap(ip, iomap, &imap, 0, 0, seq);
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*device_generation = mp->m_generation;
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return error;
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out_unlock:
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xfs_iunlock(ip, XFS_IOLOCK_EXCL);
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return error;
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}
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/*
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* Ensure the size update falls into a valid allocated block.
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*/
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static int
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xfs_pnfs_validate_isize(
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struct xfs_inode *ip,
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xfs_off_t isize)
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{
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struct xfs_bmbt_irec imap;
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int nimaps = 1;
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int error = 0;
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xfs_ilock(ip, XFS_ILOCK_SHARED);
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error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
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&imap, &nimaps, 0);
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xfs_iunlock(ip, XFS_ILOCK_SHARED);
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if (error)
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return error;
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if (imap.br_startblock == HOLESTARTBLOCK ||
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imap.br_startblock == DELAYSTARTBLOCK ||
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imap.br_state == XFS_EXT_UNWRITTEN)
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return -EIO;
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return 0;
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}
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/*
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* Make sure the blocks described by maps are stable on disk. This includes
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* converting any unwritten extents, flushing the disk cache and updating the
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* time stamps.
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*
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* Note that we rely on the caller to always send us a timestamp update so that
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* we always commit a transaction here. If that stops being true we will have
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* to manually flush the cache here similar to what the fsync code path does
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* for datasyncs on files that have no dirty metadata.
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*/
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int
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xfs_fs_commit_blocks(
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struct inode *inode,
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struct iomap *maps,
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int nr_maps,
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struct iattr *iattr)
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{
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struct xfs_inode *ip = XFS_I(inode);
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struct xfs_mount *mp = ip->i_mount;
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struct xfs_trans *tp;
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bool update_isize = false;
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int error, i;
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loff_t size;
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ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
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xfs_ilock(ip, XFS_IOLOCK_EXCL);
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size = i_size_read(inode);
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if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
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update_isize = true;
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size = iattr->ia_size;
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}
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for (i = 0; i < nr_maps; i++) {
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u64 start, length, end;
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start = maps[i].offset;
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if (start > size)
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continue;
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end = start + maps[i].length;
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if (end > size)
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end = size;
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length = end - start;
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if (!length)
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continue;
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/*
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* Make sure reads through the pagecache see the new data.
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*/
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error = invalidate_inode_pages2_range(inode->i_mapping,
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start >> PAGE_SHIFT,
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(end - 1) >> PAGE_SHIFT);
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WARN_ON_ONCE(error);
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error = xfs_iomap_write_unwritten(ip, start, length, false);
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if (error)
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goto out_drop_iolock;
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}
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if (update_isize) {
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error = xfs_pnfs_validate_isize(ip, size);
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if (error)
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goto out_drop_iolock;
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}
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error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
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if (error)
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goto out_drop_iolock;
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xfs_ilock(ip, XFS_ILOCK_EXCL);
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xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
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xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
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ASSERT(!(iattr->ia_valid & (ATTR_UID | ATTR_GID)));
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setattr_copy(&nop_mnt_idmap, inode, iattr);
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if (update_isize) {
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i_size_write(inode, iattr->ia_size);
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ip->i_disk_size = iattr->ia_size;
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}
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xfs_trans_set_sync(tp);
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error = xfs_trans_commit(tp);
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out_drop_iolock:
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xfs_iunlock(ip, XFS_IOLOCK_EXCL);
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return error;
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}
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