xfs: store in-progress CoW allocations in the refcount btree (174edb0e) · Commits · 戴 / test

fs/xfs/libxfs/xfs_bmap.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -4631,6 +4631,17 @@ xfs_bmapi_write(
		goto error0;
		if (bma.blkno == NULLFSBLOCK)
		break;

		/*
		* If this is a CoW allocation, record the data in
		* the refcount btree for orphan recovery.
		*/
		if (whichfork == XFS_COW_FORK) {
		error = xfs_refcount_alloc_cow_extent(mp, dfops,
		bma.blkno, bma.length);
		if (error)
		goto error0;
		}
		}

		/* Deal with the allocated space we found. */

fs/xfs/libxfs/xfs_format.h

+13 −1

Original line number	Diff line number	Diff line
		@@ -1375,7 +1375,8 @@ struct xfs_owner_info {
		#define XFS_RMAP_OWN_INOBT (-6ULL) /* Inode btree blocks */
		#define XFS_RMAP_OWN_INODES (-7ULL) /* Inode chunk */
		#define XFS_RMAP_OWN_REFC (-8ULL) /* refcount tree */
		#define XFS_RMAP_OWN_MIN (-9ULL) /* guard */
		#define XFS_RMAP_OWN_COW (-9ULL) /* cow allocations */
		#define XFS_RMAP_OWN_MIN (-10ULL) /* guard */

		#define XFS_RMAP_NON_INODE_OWNER(owner) (!!((owner) & (1ULL << 63)))

		@@ -1477,6 +1478,17 @@ unsigned int xfs_refc_block(struct xfs_mount *mp);
		* data) are not tracked here. Free space is also not tracked here.
		* This is consistent with pre-reflink XFS.
		*/

		/*
		* Extents that are being used to stage a copy on write are stored
		* in the refcount btree with a refcount of 1 and the upper bit set
		* on the startblock. This speeds up mount time deletion of stale
		* staging extents because they're all at the right side of the tree.
		*/
		#define XFS_REFC_COW_START ((xfs_agblock_t)(1U << 31))
		#define REFCNTBT_COWFLAG_BITLEN 1
		#define REFCNTBT_AGBLOCK_BITLEN 31

		struct xfs_refcount_rec {
		__be32 rc_startblock; /* starting block number */
		__be32 rc_blockcount; /* count of blocks */

fs/xfs/libxfs/xfs_refcount.c

+443 −10

Original line number	Diff line number	Diff line
		@@ -36,13 +36,23 @@
		#include "xfs_trans.h"
		#include "xfs_bit.h"
		#include "xfs_refcount.h"
		#include "xfs_rmap.h"

		/* Allowable refcount adjustment amounts. */
		enum xfs_refc_adjust_op {
		XFS_REFCOUNT_ADJUST_INCREASE = 1,
		XFS_REFCOUNT_ADJUST_DECREASE = -1,
		XFS_REFCOUNT_ADJUST_COW_ALLOC = 0,
		XFS_REFCOUNT_ADJUST_COW_FREE = -1,
		};

		STATIC int __xfs_refcount_cow_alloc(struct xfs_btree_cur *rcur,
		xfs_agblock_t agbno, xfs_extlen_t aglen,
		struct xfs_defer_ops *dfops);
		STATIC int __xfs_refcount_cow_free(struct xfs_btree_cur *rcur,
		xfs_agblock_t agbno, xfs_extlen_t aglen,
		struct xfs_defer_ops *dfops);

		/*
		* Look up the first record less than or equal to [bno, len] in the btree
		* given by cur.
		@@ -77,6 +87,17 @@ xfs_refcount_lookup_ge(
		return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
		}

		/* Convert on-disk record to in-core format. */
		static inline void
		xfs_refcount_btrec_to_irec(
		union xfs_btree_rec *rec,
		struct xfs_refcount_irec *irec)
		{
		irec->rc_startblock = be32_to_cpu(rec->refc.rc_startblock);
		irec->rc_blockcount = be32_to_cpu(rec->refc.rc_blockcount);
		irec->rc_refcount = be32_to_cpu(rec->refc.rc_refcount);
		}

		/*
		* Get the data from the pointed-to record.
		*/
		@@ -91,9 +112,7 @@ xfs_refcount_get_rec(

		error = xfs_btree_get_rec(cur, &rec, stat);
		if (!error && *stat == 1) {
		irec->rc_startblock = be32_to_cpu(rec->refc.rc_startblock);
		irec->rc_blockcount = be32_to_cpu(rec->refc.rc_blockcount);
		irec->rc_refcount = be32_to_cpu(rec->refc.rc_refcount);
		xfs_refcount_btrec_to_irec(rec, irec);
		trace_xfs_refcount_get(cur->bc_mp, cur->bc_private.a.agno,
		irec);
		}
		@@ -501,6 +520,8 @@ out_error:
		return error;
		}

		#define XFS_FIND_RCEXT_SHARED 1
		#define XFS_FIND_RCEXT_COW 2
		/*
		* Find the left extent and the one after it (cleft). This function assumes
		* that we've already split any extent crossing agbno.
		@@ -511,7 +532,8 @@ xfs_refcount_find_left_extents(
		struct xfs_refcount_irec *left,
		struct xfs_refcount_irec *cleft,
		xfs_agblock_t agbno,
		xfs_extlen_t aglen)
		xfs_extlen_t aglen,
		int flags)
		{
		struct xfs_refcount_irec tmp;
		int error;
		@@ -531,6 +553,10 @@ xfs_refcount_find_left_extents(

		if (xfs_refc_next(&tmp) != agbno)
		return 0;
		if ((flags & XFS_FIND_RCEXT_SHARED) && tmp.rc_refcount < 2)
		return 0;
		if ((flags & XFS_FIND_RCEXT_COW) && tmp.rc_refcount > 1)
		return 0;
		/* We have a left extent; retrieve (or invent) the next right one */
		*left = tmp;

		@@ -590,7 +616,8 @@ xfs_refcount_find_right_extents(
		struct xfs_refcount_irec *right,
		struct xfs_refcount_irec *cright,
		xfs_agblock_t agbno,
		xfs_extlen_t aglen)
		xfs_extlen_t aglen,
		int flags)
		{
		struct xfs_refcount_irec tmp;
		int error;
		@@ -610,6 +637,10 @@ xfs_refcount_find_right_extents(

		if (tmp.rc_startblock != agbno + aglen)
		return 0;
		if ((flags & XFS_FIND_RCEXT_SHARED) && tmp.rc_refcount < 2)
		return 0;
		if ((flags & XFS_FIND_RCEXT_COW) && tmp.rc_refcount > 1)
		return 0;
		/* We have a right extent; retrieve (or invent) the next left one */
		*right = tmp;

		@@ -676,6 +707,7 @@ xfs_refcount_merge_extents(
		xfs_agblock_t *agbno,
		xfs_extlen_t *aglen,
		enum xfs_refc_adjust_op adjust,
		int flags,
		bool *shape_changed)
		{
		struct xfs_refcount_irec left = {0}, cleft = {0};
		@@ -691,11 +723,11 @@ xfs_refcount_merge_extents(
		* [right].
		*/
		error = xfs_refcount_find_left_extents(cur, &left, &cleft, *agbno,
		*aglen);
		*aglen, flags);
		if (error)
		return error;
		error = xfs_refcount_find_right_extents(cur, &right, &cright, *agbno,
		*aglen);
		*aglen, flags);
		if (error)
		return error;

		@@ -968,7 +1000,7 @@ xfs_refcount_adjust(
		* Try to merge with the left or right extents of the range.
		*/
		error = xfs_refcount_merge_extents(cur, new_agbno, new_aglen, adj,
		&shape_changed);
		XFS_FIND_RCEXT_SHARED, &shape_changed);
		if (error)
		goto out_error;
		if (shape_changed)
		@@ -1089,6 +1121,16 @@ xfs_refcount_finish_one(
		new_len, XFS_REFCOUNT_ADJUST_DECREASE, dfops, NULL);
		*new_fsb = XFS_AGB_TO_FSB(mp, agno, new_agbno);
		break;
		case XFS_REFCOUNT_ALLOC_COW:
		*new_fsb = startblock + blockcount;
		*new_len = 0;
		error = __xfs_refcount_cow_alloc(rcur, bno, blockcount, dfops);
		break;
		case XFS_REFCOUNT_FREE_COW:
		*new_fsb = startblock + blockcount;
		*new_len = 0;
		error = __xfs_refcount_cow_free(rcur, bno, blockcount, dfops);
		break;
		default:
		ASSERT(0);
		error = -EFSCORRUPTED;
		@@ -1265,3 +1307,394 @@ out_error:
		cur->bc_private.a.agno, error, _RET_IP_);
		return error;
		}

		/*
		* Recovering CoW Blocks After a Crash
		*
		* Due to the way that the copy on write mechanism works, there's a window of
		* opportunity in which we can lose track of allocated blocks during a crash.
		* Because CoW uses delayed allocation in the in-core CoW fork, writeback
		* causes blocks to be allocated and stored in the CoW fork. The blocks are
		* no longer in the free space btree but are not otherwise recorded anywhere
		* until the write completes and the blocks are mapped into the file. A crash
		* in between allocation and remapping results in the replacement blocks being
		* lost. This situation is exacerbated by the CoW extent size hint because
		* allocations can hang around for long time.
		*
		* However, there is a place where we can record these allocations before they
		* become mappings -- the reference count btree. The btree does not record
		* extents with refcount == 1, so we can record allocations with a refcount of
		* 1. Blocks being used for CoW writeout cannot be shared, so there should be
		* no conflict with shared block records. These mappings should be created
		* when we allocate blocks to the CoW fork and deleted when they're removed
		* from the CoW fork.
		*
		* Minor nit: records for in-progress CoW allocations and records for shared
		* extents must never be merged, to preserve the property that (except for CoW
		* allocations) there are no refcount btree entries with refcount == 1. The
		* only time this could potentially happen is when unsharing a block that's
		* adjacent to CoW allocations, so we must be careful to avoid this.
		*
		* At mount time we recover lost CoW allocations by searching the refcount
		* btree for these refcount == 1 mappings. These represent CoW allocations
		* that were in progress at the time the filesystem went down, so we can free
		* them to get the space back.
		*
		* This mechanism is superior to creating EFIs for unmapped CoW extents for
		* several reasons -- first, EFIs pin the tail of the log and would have to be
		* periodically relogged to avoid filling up the log. Second, CoW completions
		* will have to file an EFD and create new EFIs for whatever remains in the
		* CoW fork; this partially takes care of (1) but extent-size reservations
		* will have to periodically relog even if there's no writeout in progress.
		* This can happen if the CoW extent size hint is set, which you really want.
		* Third, EFIs cannot currently be automatically relogged into newer
		* transactions to advance the log tail. Fourth, stuffing the log full of
		* EFIs places an upper bound on the number of CoW allocations that can be
		* held filesystem-wide at any given time. Recording them in the refcount
		* btree doesn't require us to maintain any state in memory and doesn't pin
		* the log.
		*/
		/*
		* Adjust the refcounts of CoW allocations. These allocations are "magic"
		* in that they're not referenced anywhere else in the filesystem, so we
		* stash them in the refcount btree with a refcount of 1 until either file
		* remapping (or CoW cancellation) happens.
		*/
		STATIC int
		xfs_refcount_adjust_cow_extents(
		struct xfs_btree_cur *cur,
		xfs_agblock_t agbno,
		xfs_extlen_t aglen,
		enum xfs_refc_adjust_op adj,
		struct xfs_defer_ops *dfops,
		struct xfs_owner_info *oinfo)
		{
		struct xfs_refcount_irec ext, tmp;
		int error;
		int found_rec, found_tmp;

		if (aglen == 0)
		return 0;

		/* Find any overlapping refcount records */
		error = xfs_refcount_lookup_ge(cur, agbno, &found_rec);
		if (error)
		goto out_error;
		error = xfs_refcount_get_rec(cur, &ext, &found_rec);
		if (error)
		goto out_error;
		if (!found_rec) {
		ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks +
		XFS_REFC_COW_START;
		ext.rc_blockcount = 0;
		ext.rc_refcount = 0;
		}

		switch (adj) {
		case XFS_REFCOUNT_ADJUST_COW_ALLOC:
		/* Adding a CoW reservation, there should be nothing here. */
		XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
		ext.rc_startblock >= agbno + aglen, out_error);

		tmp.rc_startblock = agbno;
		tmp.rc_blockcount = aglen;
		tmp.rc_refcount = 1;
		trace_xfs_refcount_modify_extent(cur->bc_mp,
		cur->bc_private.a.agno, &tmp);

		error = xfs_refcount_insert(cur, &tmp,
		&found_tmp);
		if (error)
		goto out_error;
		XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
		found_tmp == 1, out_error);
		break;
		case XFS_REFCOUNT_ADJUST_COW_FREE:
		/* Removing a CoW reservation, there should be one extent. */
		XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
		ext.rc_startblock == agbno, out_error);
		XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
		ext.rc_blockcount == aglen, out_error);
		XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
		ext.rc_refcount == 1, out_error);

		ext.rc_refcount = 0;
		trace_xfs_refcount_modify_extent(cur->bc_mp,
		cur->bc_private.a.agno, &ext);
		error = xfs_refcount_delete(cur, &found_rec);
		if (error)
		goto out_error;
		XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
		found_rec == 1, out_error);
		break;
		default:
		ASSERT(0);
		}

		return error;
		out_error:
		trace_xfs_refcount_modify_extent_error(cur->bc_mp,
		cur->bc_private.a.agno, error, _RET_IP_);
		return error;
		}

		/*
		* Add or remove refcount btree entries for CoW reservations.
		*/
		STATIC int
		xfs_refcount_adjust_cow(
		struct xfs_btree_cur *cur,
		xfs_agblock_t agbno,
		xfs_extlen_t aglen,
		enum xfs_refc_adjust_op adj,
		struct xfs_defer_ops *dfops)
		{
		bool shape_changed;
		int error;

		agbno += XFS_REFC_COW_START;

		/*
		* Ensure that no rcextents cross the boundary of the adjustment range.
		*/
		error = xfs_refcount_split_extent(cur, agbno, &shape_changed);
		if (error)
		goto out_error;

		error = xfs_refcount_split_extent(cur, agbno + aglen, &shape_changed);
		if (error)
		goto out_error;

		/*
		* Try to merge with the left or right extents of the range.
		*/
		error = xfs_refcount_merge_extents(cur, &agbno, &aglen, adj,
		XFS_FIND_RCEXT_COW, &shape_changed);
		if (error)
		goto out_error;

		/* Now that we've taken care of the ends, adjust the middle extents */
		error = xfs_refcount_adjust_cow_extents(cur, agbno, aglen, adj,
		dfops, NULL);
		if (error)
		goto out_error;

		return 0;

		out_error:
		trace_xfs_refcount_adjust_cow_error(cur->bc_mp, cur->bc_private.a.agno,
		error, _RET_IP_);
		return error;
		}

		/*
		* Record a CoW allocation in the refcount btree.
		*/
		STATIC int
		__xfs_refcount_cow_alloc(
		struct xfs_btree_cur *rcur,
		xfs_agblock_t agbno,
		xfs_extlen_t aglen,
		struct xfs_defer_ops *dfops)
		{
		int error;

		trace_xfs_refcount_cow_increase(rcur->bc_mp, rcur->bc_private.a.agno,
		agbno, aglen);

		/* Add refcount btree reservation */
		error = xfs_refcount_adjust_cow(rcur, agbno, aglen,
		XFS_REFCOUNT_ADJUST_COW_ALLOC, dfops);
		if (error)
		return error;

		/* Add rmap entry */
		if (xfs_sb_version_hasrmapbt(&rcur->bc_mp->m_sb)) {
		error = xfs_rmap_alloc_extent(rcur->bc_mp, dfops,
		rcur->bc_private.a.agno,
		agbno, aglen, XFS_RMAP_OWN_COW);
		if (error)
		return error;
		}

		return error;
		}

		/*
		* Remove a CoW allocation from the refcount btree.
		*/
		STATIC int
		__xfs_refcount_cow_free(
		struct xfs_btree_cur *rcur,
		xfs_agblock_t agbno,
		xfs_extlen_t aglen,
		struct xfs_defer_ops *dfops)
		{
		int error;

		trace_xfs_refcount_cow_decrease(rcur->bc_mp, rcur->bc_private.a.agno,
		agbno, aglen);

		/* Remove refcount btree reservation */
		error = xfs_refcount_adjust_cow(rcur, agbno, aglen,
		XFS_REFCOUNT_ADJUST_COW_FREE, dfops);
		if (error)
		return error;

		/* Remove rmap entry */
		if (xfs_sb_version_hasrmapbt(&rcur->bc_mp->m_sb)) {
		error = xfs_rmap_free_extent(rcur->bc_mp, dfops,
		rcur->bc_private.a.agno,
		agbno, aglen, XFS_RMAP_OWN_COW);
		if (error)
		return error;
		}

		return error;
		}

		/* Record a CoW staging extent in the refcount btree. */
		int
		xfs_refcount_alloc_cow_extent(
		struct xfs_mount *mp,
		struct xfs_defer_ops *dfops,
		xfs_fsblock_t fsb,
		xfs_extlen_t len)
		{
		if (!xfs_sb_version_hasreflink(&mp->m_sb))
		return 0;

		return __xfs_refcount_add(mp, dfops, XFS_REFCOUNT_ALLOC_COW,
		fsb, len);
		}

		/* Forget a CoW staging event in the refcount btree. */
		int
		xfs_refcount_free_cow_extent(
		struct xfs_mount *mp,
		struct xfs_defer_ops *dfops,
		xfs_fsblock_t fsb,
		xfs_extlen_t len)
		{
		if (!xfs_sb_version_hasreflink(&mp->m_sb))
		return 0;

		return __xfs_refcount_add(mp, dfops, XFS_REFCOUNT_FREE_COW,
		fsb, len);
		}

		struct xfs_refcount_recovery {
		struct list_head rr_list;
		struct xfs_refcount_irec rr_rrec;
		};

		/* Stuff an extent on the recovery list. */
		STATIC int
		xfs_refcount_recover_extent(
		struct xfs_btree_cur *cur,
		union xfs_btree_rec *rec,
		void *priv)
		{
		struct list_head *debris = priv;
		struct xfs_refcount_recovery *rr;

		if (be32_to_cpu(rec->refc.rc_refcount) != 1)
		return -EFSCORRUPTED;

		rr = kmem_alloc(sizeof(struct xfs_refcount_recovery), KM_SLEEP);
		xfs_refcount_btrec_to_irec(rec, &rr->rr_rrec);
		list_add_tail(&rr->rr_list, debris);

		return 0;
		}

		/* Find and remove leftover CoW reservations. */
		int
		xfs_refcount_recover_cow_leftovers(
		struct xfs_mount *mp,
		xfs_agnumber_t agno)
		{
		struct xfs_trans *tp;
		struct xfs_btree_cur *cur;
		struct xfs_buf *agbp;
		struct xfs_refcount_recovery rr, n;
		struct list_head debris;
		union xfs_btree_irec low;
		union xfs_btree_irec high;
		struct xfs_defer_ops dfops;
		xfs_fsblock_t fsb;
		xfs_agblock_t agbno;
		int error;

		if (mp->m_sb.sb_agblocks >= XFS_REFC_COW_START)
		return -EOPNOTSUPP;

		error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
		if (error)
		return error;
		cur = xfs_refcountbt_init_cursor(mp, NULL, agbp, agno, NULL);

		/* Find all the leftover CoW staging extents. */
		INIT_LIST_HEAD(&debris);
		memset(&low, 0, sizeof(low));
		memset(&high, 0, sizeof(high));
		low.rc.rc_startblock = XFS_REFC_COW_START;
		high.rc.rc_startblock = -1U;
		error = xfs_btree_query_range(cur, &low, &high,
		xfs_refcount_recover_extent, &debris);
		if (error)
		goto out_error;
		xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
		xfs_buf_relse(agbp);

		/* Now iterate the list to free the leftovers */
		list_for_each_entry(rr, &debris, rr_list) {
		/* Set up transaction. */
		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
		if (error)
		goto out_free;

		trace_xfs_refcount_recover_extent(mp, agno, &rr->rr_rrec);

		/* Free the orphan record */
		xfs_defer_init(&dfops, &fsb);
		agbno = rr->rr_rrec.rc_startblock - XFS_REFC_COW_START;
		fsb = XFS_AGB_TO_FSB(mp, agno, agbno);
		error = xfs_refcount_free_cow_extent(mp, &dfops, fsb,
		rr->rr_rrec.rc_blockcount);
		if (error)
		goto out_defer;

		/* Free the block. */
		xfs_bmap_add_free(mp, &dfops, fsb,
		rr->rr_rrec.rc_blockcount, NULL);

		error = xfs_defer_finish(&tp, &dfops, NULL);
		if (error)
		goto out_defer;

		error = xfs_trans_commit(tp);
		if (error)
		goto out_cancel;
		}
		goto out_free;

		out_defer:
		xfs_defer_cancel(&dfops);
		out_cancel:
		xfs_trans_cancel(tp);

		out_free:
		/* Free the leftover list */
		list_for_each_entry_safe(rr, n, &debris, rr_list) {
		list_del(&rr->rr_list);
		kmem_free(rr);
		}

		return error;

		out_error:
		xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
		xfs_buf_relse(agbp);
		return error;
		}

fs/xfs/libxfs/xfs_refcount.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -58,4 +58,13 @@ extern int xfs_refcount_find_shared(struct xfs_btree_cur *cur,
		xfs_agblock_t agbno, xfs_extlen_t aglen, xfs_agblock_t *fbno,
		xfs_extlen_t *flen, bool find_end_of_shared);

		extern int xfs_refcount_alloc_cow_extent(struct xfs_mount *mp,
		struct xfs_defer_ops *dfops, xfs_fsblock_t fsb,
		xfs_extlen_t len);
		extern int xfs_refcount_free_cow_extent(struct xfs_mount *mp,
		struct xfs_defer_ops *dfops, xfs_fsblock_t fsb,
		xfs_extlen_t len);
		extern int xfs_refcount_recover_cow_leftovers(struct xfs_mount *mp,
		xfs_agnumber_t agno);

		#endif /* __XFS_REFCOUNT_H__ */

fs/xfs/xfs_mount.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -44,6 +44,7 @@
		#include "xfs_sysfs.h"
		#include "xfs_rmap_btree.h"
		#include "xfs_refcount_btree.h"
		#include "xfs_reflink.h"


		static DEFINE_MUTEX(xfs_uuid_table_mutex);
		@@ -985,10 +986,21 @@ xfs_mountfs(
		if (error)
		xfs_warn(mp,
		"Unable to allocate reserve blocks. Continuing without reserve pool.");

		/* Recover any CoW blocks that never got remapped. */
		error = xfs_reflink_recover_cow(mp);
		if (error) {
		xfs_err(mp,
		"Error %d recovering leftover CoW allocations.", error);
		xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
		goto out_quota;
		}
		}

		return 0;

		out_quota:
		xfs_qm_unmount_quotas(mp);
		out_rtunmount:
		xfs_rtunmount_inodes(mp);
		out_rele_rip:

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