fs/xfs/xfs_fsops.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (c) 2000-2005 Silicon Graphics, Inc.
  * All Rights Reserved.
  */
 #include "xfs.h"
 #include "xfs_fs.h"
 #include "xfs_shared.h"
 #include "xfs_format.h"
 #include "xfs_log_format.h"
 #include "xfs_trans_resv.h"
 #include "xfs_sb.h"
 #include "xfs_mount.h"
 #include "xfs_trans.h"
 #include "xfs_error.h"
 #include "xfs_alloc.h"
 #include "xfs_fsops.h"
 #include "xfs_trans_space.h"
 #include "xfs_log.h"
 #include "xfs_log_priv.h"
 #include "xfs_ag.h"
 #include "xfs_ag_resv.h"
 #include "xfs_trace.h"

 /*
  * Write new AG headers to disk. Non-transactional, but need to be
  * written and completed prior to the growfs transaction being logged.
  * To do this, we use a delayed write buffer list and wait for
  * submission and IO completion of the list as a whole. This allows the
  * IO subsystem to merge all the AG headers in a single AG into a single
  * IO and hide most of the latency of the IO from us.
  *
  * This also means that if we get an error whilst building the buffer
  * list to write, we can cancel the entire list without having written
  * anything.
  */
 static int
 xfs_resizefs_init_new_ags(
 	struct xfs_trans	*tp,
 	struct aghdr_init_data	*id,
 	xfs_agnumber_t		oagcount,
 	xfs_agnumber_t		nagcount,
 	xfs_rfsblock_t		delta,
 	struct xfs_perag	*last_pag,
 	bool			*lastag_extended)
 {
 	struct xfs_mount	*mp = tp->t_mountp;
 	xfs_rfsblock_t		nb = mp->m_sb.sb_dblocks + delta;
 	int			error;

 	*lastag_extended = false;

 	INIT_LIST_HEAD(&id->buffer_list);
 	for (id->agno = nagcount - 1;
 	     id->agno >= oagcount;
 	     id->agno--, delta -= id->agsize) {

 		if (id->agno == nagcount - 1)
 			id->agsize = nb - (id->agno *
 					(xfs_rfsblock_t)mp->m_sb.sb_agblocks);
 		else
 			id->agsize = mp->m_sb.sb_agblocks;

 		error = xfs_ag_init_headers(mp, id);
 		if (error) {
 			xfs_buf_delwri_cancel(&id->buffer_list);
 			return error;
 		}
 	}

 	error = xfs_buf_delwri_submit(&id->buffer_list);
 	if (error)
 		return error;

 	if (delta) {
 		*lastag_extended = true;
 		error = xfs_ag_extend_space(last_pag, tp, delta);
 	}
 	return error;
 }

 /*
  * growfs operations
  */
 static int
 xfs_growfs_data_private(
 	struct xfs_mount	*mp,		/* mount point for filesystem */
 	struct xfs_growfs_data	*in)		/* growfs data input struct */
 {
 	xfs_agnumber_t		oagcount = mp->m_sb.sb_agcount;
 	struct xfs_buf		*bp;
 	int			error;
 	xfs_agnumber_t		nagcount;
 	xfs_agnumber_t		nagimax = 0;
 	xfs_rfsblock_t		nb, nb_div, nb_mod;
 	int64_t			delta;
 	bool			lastag_extended = false;
 	struct xfs_trans	*tp;
 	struct aghdr_init_data	id = {};
 	struct xfs_perag	*last_pag;

 	nb = in->newblocks;
 	error = xfs_sb_validate_fsb_count(&mp->m_sb, nb);
 	if (error)
 		return error;

 	if (nb > mp->m_sb.sb_dblocks) {
 		error = xfs_buf_read_uncached(mp->m_ddev_targp,
 				XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
 				XFS_FSS_TO_BB(mp, 1), 0, &bp, NULL);
 		if (error)
 			return error;
 		xfs_buf_relse(bp);
 	}

 	nb_div = nb;
 	nb_mod = do_div(nb_div, mp->m_sb.sb_agblocks);
 	if (nb_mod && nb_mod >= XFS_MIN_AG_BLOCKS)
 		nb_div++;
 	else if (nb_mod)
 		nb = nb_div * mp->m_sb.sb_agblocks;

 	if (nb_div > XFS_MAX_AGNUMBER + 1) {
 		nb_div = XFS_MAX_AGNUMBER + 1;
 		nb = nb_div * mp->m_sb.sb_agblocks;
 	}
 	nagcount = nb_div;
 	delta = nb - mp->m_sb.sb_dblocks;
 	/*
 	 * Reject filesystems with a single AG because they are not
 	 * supported, and reject a shrink operation that would cause a
 	 * filesystem to become unsupported.
 	 */
 	if (delta < 0 && nagcount < 2)
 		return -EINVAL;

 	/* No work to do */
 	if (delta == 0)
 		return 0;

 	/* TODO: shrinking the entire AGs hasn't yet completed */
 	if (nagcount < oagcount)
 		return -EINVAL;

 	/* allocate the new per-ag structures */
 	error = xfs_initialize_perag(mp, oagcount, nagcount, nb, &nagimax);
 	if (error)
 		return error;

 	if (delta > 0)
 		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata,
 				XFS_GROWFS_SPACE_RES(mp), 0, XFS_TRANS_RESERVE,
 				&tp);
 	else
 		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata, -delta, 0,
 				0, &tp);
 	if (error)
 		goto out_free_unused_perag;

 	last_pag = xfs_perag_get(mp, oagcount - 1);
 	if (delta > 0) {
 		error = xfs_resizefs_init_new_ags(tp, &id, oagcount, nagcount,
 				delta, last_pag, &lastag_extended);
 	} else {
 		xfs_warn_experimental(mp, XFS_EXPERIMENTAL_SHRINK);
 		error = xfs_ag_shrink_space(last_pag, &tp, -delta);
 	}
 	xfs_perag_put(last_pag);
 	if (error)
 		goto out_trans_cancel;

 	/*
 	 * Update changed superblock fields transactionally. These are not
 	 * seen by the rest of the world until the transaction commit applies
 	 * them atomically to the superblock.
 	 */
 	if (nagcount > oagcount)
 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount);
 	if (delta)
 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_DBLOCKS, delta);
 	if (id.nfree)
 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, id.nfree);

 	/*
 	 * Sync sb counters now to reflect the updated values. This is
 	 * particularly important for shrink because the write verifier
 	 * will fail if sb_fdblocks is ever larger than sb_dblocks.
 	 */
 	if (xfs_has_lazysbcount(mp))
 		xfs_log_sb(tp);

 	xfs_trans_set_sync(tp);
 	error = xfs_trans_commit(tp);
 	if (error)
 		return error;

 	/* New allocation groups fully initialized, so update mount struct */
 	if (nagimax)
 		mp->m_maxagi = nagimax;
 	xfs_set_low_space_thresholds(mp);
 	mp->m_alloc_set_aside = xfs_alloc_set_aside(mp);

 	if (delta > 0) {
 		/*
 		 * If we expanded the last AG, free the per-AG reservation
 		 * so we can reinitialize it with the new size.
 		 */
 		if (lastag_extended) {
 			struct xfs_perag	*pag;

 			pag = xfs_perag_get(mp, id.agno);
 			xfs_ag_resv_free(pag);
 			xfs_perag_put(pag);
 		}
 		/*
 		 * Reserve AG metadata blocks. ENOSPC here does not mean there
 		 * was a growfs failure, just that there still isn't space for
 		 * new user data after the grow has been run.
 		 */
 		error = xfs_fs_reserve_ag_blocks(mp);
 		if (error == -ENOSPC)
 			error = 0;
 	}
 	return error;

 out_trans_cancel:
 	xfs_trans_cancel(tp);
 out_free_unused_perag:
 	if (nagcount > oagcount)
 		xfs_free_perag_range(mp, oagcount, nagcount);
 	return error;
 }

 static int
 xfs_growfs_log_private(
 	struct xfs_mount	*mp,	/* mount point for filesystem */
 	struct xfs_growfs_log	*in)	/* growfs log input struct */
 {
 	xfs_extlen_t		nb;

 	nb = in->newblocks;
 	if (nb < XFS_MIN_LOG_BLOCKS || nb < XFS_B_TO_FSB(mp, XFS_MIN_LOG_BYTES))
 		return -EINVAL;
 	if (nb == mp->m_sb.sb_logblocks &&
 	    in->isint == (mp->m_sb.sb_logstart != 0))
 		return -EINVAL;
 	/*
 	 * Moving the log is hard, need new interfaces to sync
 	 * the log first, hold off all activity while moving it.
 	 * Can have shorter or longer log in the same space,
 	 * or transform internal to external log or vice versa.
 	 */
 	return -ENOSYS;
 }

 static int
 xfs_growfs_imaxpct(
 	struct xfs_mount	*mp,
 	__u32			imaxpct)
 {
 	struct xfs_trans	*tp;
 	int			dpct;
 	int			error;

 	if (imaxpct > 100)
 		return -EINVAL;

 	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata,
 			XFS_GROWFS_SPACE_RES(mp), 0, XFS_TRANS_RESERVE, &tp);
 	if (error)
 		return error;

 	dpct = imaxpct - mp->m_sb.sb_imax_pct;
 	xfs_trans_mod_sb(tp, XFS_TRANS_SB_IMAXPCT, dpct);
 	xfs_trans_set_sync(tp);
 	return xfs_trans_commit(tp);
 }

 /*
  * protected versions of growfs function acquire and release locks on the mount
  * point - exported through ioctls: XFS_IOC_FSGROWFSDATA, XFS_IOC_FSGROWFSLOG,
  * XFS_IOC_FSGROWFSRT
  */
 int
 xfs_growfs_data(
 	struct xfs_mount	*mp,
 	struct xfs_growfs_data	*in)
 {
 	int			error = 0;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 	if (!mutex_trylock(&mp->m_growlock))
 		return -EWOULDBLOCK;

 	/* update imaxpct separately to the physical grow of the filesystem */
 	if (in->imaxpct != mp->m_sb.sb_imax_pct) {
 		error = xfs_growfs_imaxpct(mp, in->imaxpct);
 		if (error)
 			goto out_error;
 	}

 	if (in->newblocks != mp->m_sb.sb_dblocks) {
 		error = xfs_growfs_data_private(mp, in);
 		if (error)
 			goto out_error;
 	}

 	/* Post growfs calculations needed to reflect new state in operations */
 	if (mp->m_sb.sb_imax_pct) {
 		uint64_t icount = mp->m_sb.sb_dblocks * mp->m_sb.sb_imax_pct;
 		do_div(icount, 100);
 		M_IGEO(mp)->maxicount = XFS_FSB_TO_INO(mp, icount);
 	} else
 		M_IGEO(mp)->maxicount = 0;

 	/* Update secondary superblocks now the physical grow has completed */
 	error = xfs_update_secondary_sbs(mp);

 out_error:
 	/*
 	 * Increment the generation unconditionally, the error could be from
 	 * updating the secondary superblocks, in which case the new size
 	 * is live already.
 	 */
 	mp->m_generation++;
 	mutex_unlock(&mp->m_growlock);
 	return error;
 }

 int
 xfs_growfs_log(
 	xfs_mount_t		*mp,
 	struct xfs_growfs_log	*in)
 {
 	int error;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 	if (!mutex_trylock(&mp->m_growlock))
 		return -EWOULDBLOCK;
 	error = xfs_growfs_log_private(mp, in);
 	mutex_unlock(&mp->m_growlock);
 	return error;
 }

 /*
  * Reserve the requested number of blocks if available. Otherwise return
  * as many as possible to satisfy the request. The actual number
  * reserved are returned in outval.
  */
 int
 xfs_reserve_blocks(
 	struct xfs_mount	*mp,
 	uint64_t		request)
 {
 	int64_t			lcounter, delta;
 	int64_t			fdblks_delta = 0;
 	int64_t			free;
 	int			error = 0;

 	/*
 	 * With per-cpu counters, this becomes an interesting problem. we need
 	 * to work out if we are freeing or allocation blocks first, then we can
 	 * do the modification as necessary.
 	 *
 	 * We do this under the m_sb_lock so that if we are near ENOSPC, we will
 	 * hold out any changes while we work out what to do. This means that
 	 * the amount of free space can change while we do this, so we need to
 	 * retry if we end up trying to reserve more space than is available.
 	 */
 	spin_lock(&mp->m_sb_lock);

 	/*
 	 * If our previous reservation was larger than the current value,
 	 * then move any unused blocks back to the free pool. Modify the resblks
 	 * counters directly since we shouldn't have any problems unreserving
 	 * space.
 	 */
 	if (mp->m_resblks > request) {
 		lcounter = mp->m_resblks_avail - request;
 		if (lcounter > 0) {		/* release unused blocks */
 			fdblks_delta = lcounter;
 			mp->m_resblks_avail -= lcounter;
 		}
 		mp->m_resblks = request;
 		if (fdblks_delta) {
 			spin_unlock(&mp->m_sb_lock);
 			xfs_add_fdblocks(mp, fdblks_delta);
 			spin_lock(&mp->m_sb_lock);
 		}

 		goto out;
 	}

 	/*
 	 * If the request is larger than the current reservation, reserve the
 	 * blocks before we update the reserve counters. Sample m_fdblocks and
 	 * perform a partial reservation if the request exceeds free space.
 	 *
 	 * The code below estimates how many blocks it can request from
 	 * fdblocks to stash in the reserve pool.  This is a classic TOCTOU
 	 * race since fdblocks updates are not always coordinated via
 	 * m_sb_lock.  Set the reserve size even if there's not enough free
 	 * space to fill it because mod_fdblocks will refill an undersized
 	 * reserve when it can.
 	 */
 	free = percpu_counter_sum(&mp->m_fdblocks) -
 						xfs_fdblocks_unavailable(mp);
 	delta = request - mp->m_resblks;
 	mp->m_resblks = request;
 	if (delta > 0 && free > 0) {
 		/*
 		 * We'll either succeed in getting space from the free block
 		 * count or we'll get an ENOSPC.  Don't set the reserved flag
 		 * here - we don't want to reserve the extra reserve blocks
 		 * from the reserve.
 		 *
 		 * The desired reserve size can change after we drop the lock.
 		 * Use mod_fdblocks to put the space into the reserve or into
 		 * fdblocks as appropriate.
 		 */
 		fdblks_delta = min(free, delta);
 		spin_unlock(&mp->m_sb_lock);
 		error = xfs_dec_fdblocks(mp, fdblks_delta, 0);
 		if (!error)
 			xfs_add_fdblocks(mp, fdblks_delta);
 		spin_lock(&mp->m_sb_lock);
 	}
 out:
 	spin_unlock(&mp->m_sb_lock);
 	return error;
 }

 int
 xfs_fs_goingdown(
 	xfs_mount_t	*mp,
 	uint32_t	inflags)
 {
 	switch (inflags) {
 	case XFS_FSOP_GOING_FLAGS_DEFAULT: {
 		if (!bdev_freeze(mp->m_super->s_bdev)) {
 			xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
 			bdev_thaw(mp->m_super->s_bdev);
 		}
 		break;
 	}
 	case XFS_FSOP_GOING_FLAGS_LOGFLUSH:
 		xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
 		break;
 	case XFS_FSOP_GOING_FLAGS_NOLOGFLUSH:
 		xfs_force_shutdown(mp,
 				SHUTDOWN_FORCE_UMOUNT | SHUTDOWN_LOG_IO_ERROR);
 		break;
 	default:
 		return -EINVAL;
 	}

 	return 0;
 }

 /*
  * Force a shutdown of the filesystem instantly while keeping the filesystem
  * consistent. We don't do an unmount here; just shutdown the shop, make sure
  * that absolutely nothing persistent happens to this filesystem after this
  * point.
  *
  * The shutdown state change is atomic, resulting in the first and only the
  * first shutdown call processing the shutdown. This means we only shutdown the
  * log once as it requires, and we don't spam the logs when multiple concurrent
  * shutdowns race to set the shutdown flags.
  */
 void
 xfs_do_force_shutdown(
 	struct xfs_mount *mp,
 	uint32_t	flags,
 	char		*fname,
 	int		lnnum)
 {
 	int		tag;
 	const char	*why;


 	if (xfs_set_shutdown(mp)) {
 		xlog_shutdown_wait(mp->m_log);
 		return;
 	}
 	if (mp->m_sb_bp)
 		mp->m_sb_bp->b_flags |= XBF_DONE;

 	if (flags & SHUTDOWN_FORCE_UMOUNT)
 		xfs_alert(mp, "User initiated shutdown received.");

 	if (xlog_force_shutdown(mp->m_log, flags)) {
 		tag = XFS_PTAG_SHUTDOWN_LOGERROR;
 		why = "Log I/O Error";
 	} else if (flags & SHUTDOWN_CORRUPT_INCORE) {
 		tag = XFS_PTAG_SHUTDOWN_CORRUPT;
 		why = "Corruption of in-memory data";
 	} else if (flags & SHUTDOWN_CORRUPT_ONDISK) {
 		tag = XFS_PTAG_SHUTDOWN_CORRUPT;
 		why = "Corruption of on-disk metadata";
 	} else if (flags & SHUTDOWN_DEVICE_REMOVED) {
 		tag = XFS_PTAG_SHUTDOWN_IOERROR;
 		why = "Block device removal";
 	} else {
 		tag = XFS_PTAG_SHUTDOWN_IOERROR;
 		why = "Metadata I/O Error";
 	}

 	trace_xfs_force_shutdown(mp, tag, flags, fname, lnnum);

 	xfs_alert_tag(mp, tag,
 "%s (0x%x) detected at %pS (%s:%d).  Shutting down filesystem.",
 			why, flags, __return_address, fname, lnnum);
 	xfs_alert(mp,
 		"Please unmount the filesystem and rectify the problem(s)");
 	if (xfs_error_level >= XFS_ERRLEVEL_HIGH)
 		xfs_stack_trace();
 }

 /*
  * Reserve free space for per-AG metadata.
  */
 int
 xfs_fs_reserve_ag_blocks(
 	struct xfs_mount	*mp)
 {
 	struct xfs_perag	*pag = NULL;
 	int			error = 0;
 	int			err2;

 	mp->m_finobt_nores = false;
 	while ((pag = xfs_perag_next(mp, pag))) {
 		err2 = xfs_ag_resv_init(pag, NULL);
 		if (err2 && !error)
 			error = err2;
 	}

 	if (error && error != -ENOSPC) {
 		xfs_warn(mp,
 	"Error %d reserving per-AG metadata reserve pool.", error);
 		xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
 	}

 	return error;
 }

 /*
  * Free space reserved for per-AG metadata.
  */
 void
 xfs_fs_unreserve_ag_blocks(
 	struct xfs_mount	*mp)
 {
 	struct xfs_perag	*pag = NULL;

 	while ((pag = xfs_perag_next(mp, pag)))
 		xfs_ag_resv_free(pag);
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (c) 2000-2005 Silicon Graphics, Inc.
	* All Rights Reserved.
	*/
	#include "xfs.h"
	#include "xfs_fs.h"
	#include "xfs_shared.h"
	#include "xfs_format.h"
	#include "xfs_log_format.h"
	#include "xfs_trans_resv.h"
	#include "xfs_sb.h"
	#include "xfs_mount.h"
	#include "xfs_trans.h"
	#include "xfs_error.h"
	#include "xfs_alloc.h"
	#include "xfs_fsops.h"
	#include "xfs_trans_space.h"
	#include "xfs_log.h"
	#include "xfs_log_priv.h"
	#include "xfs_ag.h"
	#include "xfs_ag_resv.h"
	#include "xfs_trace.h"

	/*
	* Write new AG headers to disk. Non-transactional, but need to be
	* written and completed prior to the growfs transaction being logged.
	* To do this, we use a delayed write buffer list and wait for
	* submission and IO completion of the list as a whole. This allows the
	* IO subsystem to merge all the AG headers in a single AG into a single
	* IO and hide most of the latency of the IO from us.
	*
	* This also means that if we get an error whilst building the buffer
	* list to write, we can cancel the entire list without having written
	* anything.
	*/
	static int
	xfs_resizefs_init_new_ags(
	struct xfs_trans *tp,
	struct aghdr_init_data *id,
	xfs_agnumber_t oagcount,
	xfs_agnumber_t nagcount,
	xfs_rfsblock_t delta,
	struct xfs_perag *last_pag,
	bool *lastag_extended)
	{
	struct xfs_mount *mp = tp->t_mountp;
	xfs_rfsblock_t nb = mp->m_sb.sb_dblocks + delta;
	int error;

	*lastag_extended = false;

	INIT_LIST_HEAD(&id->buffer_list);
	for (id->agno = nagcount - 1;
	id->agno >= oagcount;
	id->agno--, delta -= id->agsize) {

	if (id->agno == nagcount - 1)
	id->agsize = nb - (id->agno *
	(xfs_rfsblock_t)mp->m_sb.sb_agblocks);
	else
	id->agsize = mp->m_sb.sb_agblocks;

	error = xfs_ag_init_headers(mp, id);
	if (error) {
	xfs_buf_delwri_cancel(&id->buffer_list);
	return error;
	}
	}

	error = xfs_buf_delwri_submit(&id->buffer_list);
	if (error)
	return error;

	if (delta) {
	*lastag_extended = true;
	error = xfs_ag_extend_space(last_pag, tp, delta);
	}
	return error;
	}

	/*
	* growfs operations
	*/
	static int
	xfs_growfs_data_private(
	struct xfs_mount mp, / mount point for filesystem */
	struct xfs_growfs_data in) / growfs data input struct */
	{
	xfs_agnumber_t oagcount = mp->m_sb.sb_agcount;
	struct xfs_buf *bp;
	int error;
	xfs_agnumber_t nagcount;
	xfs_agnumber_t nagimax = 0;
	xfs_rfsblock_t nb, nb_div, nb_mod;
	int64_t delta;
	bool lastag_extended = false;
	struct xfs_trans *tp;
	struct aghdr_init_data id = {};
	struct xfs_perag *last_pag;

	nb = in->newblocks;
	error = xfs_sb_validate_fsb_count(&mp->m_sb, nb);
	if (error)
	return error;

	if (nb > mp->m_sb.sb_dblocks) {
	error = xfs_buf_read_uncached(mp->m_ddev_targp,
	XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
	XFS_FSS_TO_BB(mp, 1), 0, &bp, NULL);
	if (error)
	return error;
	xfs_buf_relse(bp);
	}

	nb_div = nb;
	nb_mod = do_div(nb_div, mp->m_sb.sb_agblocks);
	if (nb_mod && nb_mod >= XFS_MIN_AG_BLOCKS)
	nb_div++;
	else if (nb_mod)
	nb = nb_div * mp->m_sb.sb_agblocks;

	if (nb_div > XFS_MAX_AGNUMBER + 1) {
	nb_div = XFS_MAX_AGNUMBER + 1;
	nb = nb_div * mp->m_sb.sb_agblocks;
	}
	nagcount = nb_div;
	delta = nb - mp->m_sb.sb_dblocks;
	/*
	* Reject filesystems with a single AG because they are not
	* supported, and reject a shrink operation that would cause a
	* filesystem to become unsupported.
	*/
	if (delta < 0 && nagcount < 2)
	return -EINVAL;

	/* No work to do */
	if (delta == 0)
	return 0;

	/* TODO: shrinking the entire AGs hasn't yet completed */
	if (nagcount < oagcount)
	return -EINVAL;

	/* allocate the new per-ag structures */
	error = xfs_initialize_perag(mp, oagcount, nagcount, nb, &nagimax);
	if (error)
	return error;

	if (delta > 0)
	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata,
	XFS_GROWFS_SPACE_RES(mp), 0, XFS_TRANS_RESERVE,
	&tp);
	else
	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata, -delta, 0,
	0, &tp);
	if (error)
	goto out_free_unused_perag;

	last_pag = xfs_perag_get(mp, oagcount - 1);
	if (delta > 0) {
	error = xfs_resizefs_init_new_ags(tp, &id, oagcount, nagcount,
	delta, last_pag, &lastag_extended);
	} else {
	xfs_warn_experimental(mp, XFS_EXPERIMENTAL_SHRINK);
	error = xfs_ag_shrink_space(last_pag, &tp, -delta);
	}
	xfs_perag_put(last_pag);
	if (error)
	goto out_trans_cancel;

	/*
	* Update changed superblock fields transactionally. These are not
	* seen by the rest of the world until the transaction commit applies
	* them atomically to the superblock.
	*/
	if (nagcount > oagcount)
	xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount);
	if (delta)
	xfs_trans_mod_sb(tp, XFS_TRANS_SB_DBLOCKS, delta);
	if (id.nfree)
	xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, id.nfree);

	/*
	* Sync sb counters now to reflect the updated values. This is
	* particularly important for shrink because the write verifier
	* will fail if sb_fdblocks is ever larger than sb_dblocks.
	*/
	if (xfs_has_lazysbcount(mp))
	xfs_log_sb(tp);

	xfs_trans_set_sync(tp);
	error = xfs_trans_commit(tp);
	if (error)
	return error;

	/* New allocation groups fully initialized, so update mount struct */
	if (nagimax)
	mp->m_maxagi = nagimax;
	xfs_set_low_space_thresholds(mp);
	mp->m_alloc_set_aside = xfs_alloc_set_aside(mp);

	if (delta > 0) {
	/*
	* If we expanded the last AG, free the per-AG reservation
	* so we can reinitialize it with the new size.
	*/
	if (lastag_extended) {
	struct xfs_perag *pag;

	pag = xfs_perag_get(mp, id.agno);
	xfs_ag_resv_free(pag);
	xfs_perag_put(pag);
	}
	/*
	* Reserve AG metadata blocks. ENOSPC here does not mean there
	* was a growfs failure, just that there still isn't space for
	* new user data after the grow has been run.
	*/
	error = xfs_fs_reserve_ag_blocks(mp);
	if (error == -ENOSPC)
	error = 0;
	}
	return error;

	out_trans_cancel:
	xfs_trans_cancel(tp);
	out_free_unused_perag:
	if (nagcount > oagcount)
	xfs_free_perag_range(mp, oagcount, nagcount);
	return error;
	}

	static int
	xfs_growfs_log_private(
	struct xfs_mount mp, / mount point for filesystem */
	struct xfs_growfs_log in) / growfs log input struct */
	{
	xfs_extlen_t nb;

	nb = in->newblocks;
	if (nb < XFS_MIN_LOG_BLOCKS \|\| nb < XFS_B_TO_FSB(mp, XFS_MIN_LOG_BYTES))
	return -EINVAL;
	if (nb == mp->m_sb.sb_logblocks &&
	in->isint == (mp->m_sb.sb_logstart != 0))
	return -EINVAL;
	/*
	* Moving the log is hard, need new interfaces to sync
	* the log first, hold off all activity while moving it.
	* Can have shorter or longer log in the same space,
	* or transform internal to external log or vice versa.
	*/
	return -ENOSYS;
	}

	static int
	xfs_growfs_imaxpct(
	struct xfs_mount *mp,
	__u32 imaxpct)
	{
	struct xfs_trans *tp;
	int dpct;
	int error;

	if (imaxpct > 100)
	return -EINVAL;

	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata,
	XFS_GROWFS_SPACE_RES(mp), 0, XFS_TRANS_RESERVE, &tp);
	if (error)
	return error;

	dpct = imaxpct - mp->m_sb.sb_imax_pct;
	xfs_trans_mod_sb(tp, XFS_TRANS_SB_IMAXPCT, dpct);
	xfs_trans_set_sync(tp);
	return xfs_trans_commit(tp);
	}

	/*
	* protected versions of growfs function acquire and release locks on the mount
	* point - exported through ioctls: XFS_IOC_FSGROWFSDATA, XFS_IOC_FSGROWFSLOG,
	* XFS_IOC_FSGROWFSRT
	*/
	int
	xfs_growfs_data(
	struct xfs_mount *mp,
	struct xfs_growfs_data *in)
	{
	int error = 0;

	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;
	if (!mutex_trylock(&mp->m_growlock))
	return -EWOULDBLOCK;

	/* update imaxpct separately to the physical grow of the filesystem */
	if (in->imaxpct != mp->m_sb.sb_imax_pct) {
	error = xfs_growfs_imaxpct(mp, in->imaxpct);
	if (error)
	goto out_error;
	}

	if (in->newblocks != mp->m_sb.sb_dblocks) {
	error = xfs_growfs_data_private(mp, in);
	if (error)
	goto out_error;
	}

	/* Post growfs calculations needed to reflect new state in operations */
	if (mp->m_sb.sb_imax_pct) {
	uint64_t icount = mp->m_sb.sb_dblocks * mp->m_sb.sb_imax_pct;
	do_div(icount, 100);
	M_IGEO(mp)->maxicount = XFS_FSB_TO_INO(mp, icount);
	} else
	M_IGEO(mp)->maxicount = 0;

	/* Update secondary superblocks now the physical grow has completed */
	error = xfs_update_secondary_sbs(mp);

	out_error:
	/*
	* Increment the generation unconditionally, the error could be from
	* updating the secondary superblocks, in which case the new size
	* is live already.
	*/
	mp->m_generation++;
	mutex_unlock(&mp->m_growlock);
	return error;
	}

	int
	xfs_growfs_log(
	xfs_mount_t *mp,
	struct xfs_growfs_log *in)
	{
	int error;

	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;
	if (!mutex_trylock(&mp->m_growlock))
	return -EWOULDBLOCK;
	error = xfs_growfs_log_private(mp, in);
	mutex_unlock(&mp->m_growlock);
	return error;
	}

	/*
	* Reserve the requested number of blocks if available. Otherwise return
	* as many as possible to satisfy the request. The actual number
	* reserved are returned in outval.
	*/
	int
	xfs_reserve_blocks(
	struct xfs_mount *mp,
	uint64_t request)
	{
	int64_t lcounter, delta;
	int64_t fdblks_delta = 0;
	int64_t free;
	int error = 0;

	/*
	* With per-cpu counters, this becomes an interesting problem. we need
	* to work out if we are freeing or allocation blocks first, then we can
	* do the modification as necessary.
	*
	* We do this under the m_sb_lock so that if we are near ENOSPC, we will
	* hold out any changes while we work out what to do. This means that
	* the amount of free space can change while we do this, so we need to
	* retry if we end up trying to reserve more space than is available.
	*/
	spin_lock(&mp->m_sb_lock);

	/*
	* If our previous reservation was larger than the current value,
	* then move any unused blocks back to the free pool. Modify the resblks
	* counters directly since we shouldn't have any problems unreserving
	* space.
	*/
	if (mp->m_resblks > request) {
	lcounter = mp->m_resblks_avail - request;
	if (lcounter > 0) { /* release unused blocks */
	fdblks_delta = lcounter;
	mp->m_resblks_avail -= lcounter;
	}
	mp->m_resblks = request;
	if (fdblks_delta) {
	spin_unlock(&mp->m_sb_lock);
	xfs_add_fdblocks(mp, fdblks_delta);
	spin_lock(&mp->m_sb_lock);
	}

	goto out;
	}

	/*
	* If the request is larger than the current reservation, reserve the
	* blocks before we update the reserve counters. Sample m_fdblocks and
	* perform a partial reservation if the request exceeds free space.
	*
	* The code below estimates how many blocks it can request from
	* fdblocks to stash in the reserve pool. This is a classic TOCTOU
	* race since fdblocks updates are not always coordinated via
	* m_sb_lock. Set the reserve size even if there's not enough free
	* space to fill it because mod_fdblocks will refill an undersized
	* reserve when it can.
	*/
	free = percpu_counter_sum(&mp->m_fdblocks) -
	xfs_fdblocks_unavailable(mp);
	delta = request - mp->m_resblks;
	mp->m_resblks = request;
	if (delta > 0 && free > 0) {
	/*
	* We'll either succeed in getting space from the free block
	* count or we'll get an ENOSPC. Don't set the reserved flag
	* here - we don't want to reserve the extra reserve blocks
	* from the reserve.
	*
	* The desired reserve size can change after we drop the lock.
	* Use mod_fdblocks to put the space into the reserve or into
	* fdblocks as appropriate.
	*/
	fdblks_delta = min(free, delta);
	spin_unlock(&mp->m_sb_lock);
	error = xfs_dec_fdblocks(mp, fdblks_delta, 0);
	if (!error)
	xfs_add_fdblocks(mp, fdblks_delta);
	spin_lock(&mp->m_sb_lock);
	}
	out:
	spin_unlock(&mp->m_sb_lock);
	return error;
	}

	int
	xfs_fs_goingdown(
	xfs_mount_t *mp,
	uint32_t inflags)
	{
	switch (inflags) {
	case XFS_FSOP_GOING_FLAGS_DEFAULT: {
	if (!bdev_freeze(mp->m_super->s_bdev)) {
	xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
	bdev_thaw(mp->m_super->s_bdev);
	}
	break;
	}
	case XFS_FSOP_GOING_FLAGS_LOGFLUSH:
	xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
	break;
	case XFS_FSOP_GOING_FLAGS_NOLOGFLUSH:
	xfs_force_shutdown(mp,
	SHUTDOWN_FORCE_UMOUNT \| SHUTDOWN_LOG_IO_ERROR);
	break;
	default:
	return -EINVAL;
	}

	return 0;
	}

	/*
	* Force a shutdown of the filesystem instantly while keeping the filesystem
	* consistent. We don't do an unmount here; just shutdown the shop, make sure
	* that absolutely nothing persistent happens to this filesystem after this
	* point.
	*
	* The shutdown state change is atomic, resulting in the first and only the
	* first shutdown call processing the shutdown. This means we only shutdown the
	* log once as it requires, and we don't spam the logs when multiple concurrent
	* shutdowns race to set the shutdown flags.
	*/
	void
	xfs_do_force_shutdown(
	struct xfs_mount *mp,
	uint32_t flags,
	char *fname,
	int lnnum)
	{
	int tag;
	const char *why;


	if (xfs_set_shutdown(mp)) {
	xlog_shutdown_wait(mp->m_log);
	return;
	}
	if (mp->m_sb_bp)
	mp->m_sb_bp->b_flags \|= XBF_DONE;

	if (flags & SHUTDOWN_FORCE_UMOUNT)
	xfs_alert(mp, "User initiated shutdown received.");

	if (xlog_force_shutdown(mp->m_log, flags)) {
	tag = XFS_PTAG_SHUTDOWN_LOGERROR;
	why = "Log I/O Error";
	} else if (flags & SHUTDOWN_CORRUPT_INCORE) {
	tag = XFS_PTAG_SHUTDOWN_CORRUPT;
	why = "Corruption of in-memory data";
	} else if (flags & SHUTDOWN_CORRUPT_ONDISK) {
	tag = XFS_PTAG_SHUTDOWN_CORRUPT;
	why = "Corruption of on-disk metadata";
	} else if (flags & SHUTDOWN_DEVICE_REMOVED) {
	tag = XFS_PTAG_SHUTDOWN_IOERROR;
	why = "Block device removal";
	} else {
	tag = XFS_PTAG_SHUTDOWN_IOERROR;
	why = "Metadata I/O Error";
	}

	trace_xfs_force_shutdown(mp, tag, flags, fname, lnnum);

	xfs_alert_tag(mp, tag,
	"%s (0x%x) detected at %pS (%s:%d). Shutting down filesystem.",
	why, flags, __return_address, fname, lnnum);
	xfs_alert(mp,
	"Please unmount the filesystem and rectify the problem(s)");
	if (xfs_error_level >= XFS_ERRLEVEL_HIGH)
	xfs_stack_trace();
	}

	/*
	* Reserve free space for per-AG metadata.
	*/
	int
	xfs_fs_reserve_ag_blocks(
	struct xfs_mount *mp)
	{
	struct xfs_perag *pag = NULL;
	int error = 0;
	int err2;

	mp->m_finobt_nores = false;
	while ((pag = xfs_perag_next(mp, pag))) {
	err2 = xfs_ag_resv_init(pag, NULL);
	if (err2 && !error)
	error = err2;
	}

	if (error && error != -ENOSPC) {
	xfs_warn(mp,
	"Error %d reserving per-AG metadata reserve pool.", error);
	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
	}

	return error;
	}

	/*
	* Free space reserved for per-AG metadata.
	*/
	void
	xfs_fs_unreserve_ag_blocks(
	struct xfs_mount *mp)
	{
	struct xfs_perag *pag = NULL;

	while ((pag = xfs_perag_next(mp, pag)))
	xfs_ag_resv_free(pag);
	}