xfs: move busy extent handling to it's own file (efc27b52) · Commits · 戴 / test

fs/xfs/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -33,6 +33,7 @@ xfs-y += xfs_aops.o \
		xfs_discard.o \
		xfs_error.o \
		xfs_export.o \
		xfs_extent_busy.o \
		xfs_file.o \
		xfs_filestream.o \
		xfs_fsops.o \

fs/xfs/xfs_ag.h

+0 −18

Original line number	Diff line number	Diff line
		@@ -174,24 +174,6 @@ typedef struct xfs_agfl {
		__be32 agfl_bno[1]; /* actually XFS_AGFL_SIZE(mp) */
		} xfs_agfl_t;

		/*
		* Busy block/extent entry. Indexed by a rbtree in perag to mark blocks that
		* have been freed but whose transactions aren't committed to disk yet.
		*
		* Note that we use the transaction ID to record the transaction, not the
		* transaction structure itself. See xfs_alloc_busy_insert() for details.
		*/
		struct xfs_busy_extent {
		struct rb_node rb_node; /* ag by-bno indexed search tree */
		struct list_head list; /* transaction busy extent list */
		xfs_agnumber_t agno;
		xfs_agblock_t bno;
		xfs_extlen_t length;
		unsigned int flags;
		#define XFS_ALLOC_BUSY_DISCARDED 0x01 /* undergoing a discard op. */
		#define XFS_ALLOC_BUSY_SKIP_DISCARD 0x02 /* do not discard */
		};

		/*
		* Per-ag incore structure, copies of information in agf and agi,
		* to improve the performance of allocation group selection.

fs/xfs/xfs_alloc.c

+1 −571

Original line number	Diff line number	Diff line
		@@ -31,6 +31,7 @@
		#include "xfs_inode.h"
		#include "xfs_btree.h"
		#include "xfs_alloc.h"
		#include "xfs_extent_busy.h"
		#include "xfs_error.h"
		#include "xfs_trace.h"

		@@ -2500,574 +2501,3 @@ error0:
		xfs_perag_put(args.pag);
		return error;
		}

		void
		xfs_alloc_busy_insert(
		struct xfs_trans *tp,
		xfs_agnumber_t agno,
		xfs_agblock_t bno,
		xfs_extlen_t len,
		unsigned int flags)
		{
		struct xfs_busy_extent *new;
		struct xfs_busy_extent *busyp;
		struct xfs_perag *pag;
		struct rb_node **rbp;
		struct rb_node *parent = NULL;

		new = kmem_zalloc(sizeof(struct xfs_busy_extent), KM_MAYFAIL);
		if (!new) {
		/*
		* No Memory! Since it is now not possible to track the free
		* block, make this a synchronous transaction to insure that
		* the block is not reused before this transaction commits.
		*/
		trace_xfs_alloc_busy_enomem(tp->t_mountp, agno, bno, len);
		xfs_trans_set_sync(tp);
		return;
		}

		new->agno = agno;
		new->bno = bno;
		new->length = len;
		INIT_LIST_HEAD(&new->list);
		new->flags = flags;

		/* trace before insert to be able to see failed inserts */
		trace_xfs_alloc_busy(tp->t_mountp, agno, bno, len);

		pag = xfs_perag_get(tp->t_mountp, new->agno);
		spin_lock(&pag->pagb_lock);
		rbp = &pag->pagb_tree.rb_node;
		while (*rbp) {
		parent = *rbp;
		busyp = rb_entry(parent, struct xfs_busy_extent, rb_node);

		if (new->bno < busyp->bno) {
		rbp = &(*rbp)->rb_left;
		ASSERT(new->bno + new->length <= busyp->bno);
		} else if (new->bno > busyp->bno) {
		rbp = &(*rbp)->rb_right;
		ASSERT(bno >= busyp->bno + busyp->length);
		} else {
		ASSERT(0);
		}
		}

		rb_link_node(&new->rb_node, parent, rbp);
		rb_insert_color(&new->rb_node, &pag->pagb_tree);

		list_add(&new->list, &tp->t_busy);
		spin_unlock(&pag->pagb_lock);
		xfs_perag_put(pag);
		}

		/*
		* Search for a busy extent within the range of the extent we are about to
		* allocate. You need to be holding the busy extent tree lock when calling
		* xfs_alloc_busy_search(). This function returns 0 for no overlapping busy
		* extent, -1 for an overlapping but not exact busy extent, and 1 for an exact
		* match. This is done so that a non-zero return indicates an overlap that
		* will require a synchronous transaction, but it can still be
		* used to distinguish between a partial or exact match.
		*/
		int
		xfs_alloc_busy_search(
		struct xfs_mount *mp,
		xfs_agnumber_t agno,
		xfs_agblock_t bno,
		xfs_extlen_t len)
		{
		struct xfs_perag *pag;
		struct rb_node *rbp;
		struct xfs_busy_extent *busyp;
		int match = 0;

		pag = xfs_perag_get(mp, agno);
		spin_lock(&pag->pagb_lock);

		rbp = pag->pagb_tree.rb_node;

		/* find closest start bno overlap */
		while (rbp) {
		busyp = rb_entry(rbp, struct xfs_busy_extent, rb_node);
		if (bno < busyp->bno) {
		/* may overlap, but exact start block is lower */
		if (bno + len > busyp->bno)
		match = -1;
		rbp = rbp->rb_left;
		} else if (bno > busyp->bno) {
		/* may overlap, but exact start block is higher */
		if (bno < busyp->bno + busyp->length)
		match = -1;
		rbp = rbp->rb_right;
		} else {
		/* bno matches busyp, length determines exact match */
		match = (busyp->length == len) ? 1 : -1;
		break;
		}
		}
		spin_unlock(&pag->pagb_lock);
		xfs_perag_put(pag);
		return match;
		}

		/*
		* The found free extent [fbno, fend] overlaps part or all of the given busy
		* extent. If the overlap covers the beginning, the end, or all of the busy
		* extent, the overlapping portion can be made unbusy and used for the
		* allocation. We can't split a busy extent because we can't modify a
		* transaction/CIL context busy list, but we can update an entries block
		* number or length.
		*
		* Returns true if the extent can safely be reused, or false if the search
		* needs to be restarted.
		*/
		STATIC bool
		xfs_alloc_busy_update_extent(
		struct xfs_mount *mp,
		struct xfs_perag *pag,
		struct xfs_busy_extent *busyp,
		xfs_agblock_t fbno,
		xfs_extlen_t flen,
		bool userdata)
		{
		xfs_agblock_t fend = fbno + flen;
		xfs_agblock_t bbno = busyp->bno;
		xfs_agblock_t bend = bbno + busyp->length;

		/*
		* This extent is currently being discarded. Give the thread
		* performing the discard a chance to mark the extent unbusy
		* and retry.
		*/
		if (busyp->flags & XFS_ALLOC_BUSY_DISCARDED) {
		spin_unlock(&pag->pagb_lock);
		delay(1);
		spin_lock(&pag->pagb_lock);
		return false;
		}

		/*
		* If there is a busy extent overlapping a user allocation, we have
		* no choice but to force the log and retry the search.
		*
		* Fortunately this does not happen during normal operation, but
		* only if the filesystem is very low on space and has to dip into
		* the AGFL for normal allocations.
		*/
		if (userdata)
		goto out_force_log;

		if (bbno < fbno && bend > fend) {
		/*
		* Case 1:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +---------+
		* fbno fend
		*/

		/*
		* We would have to split the busy extent to be able to track
		* it correct, which we cannot do because we would have to
		* modify the list of busy extents attached to the transaction
		* or CIL context, which is immutable.
		*
		* Force out the log to clear the busy extent and retry the
		* search.
		*/
		goto out_force_log;
		} else if (bbno >= fbno && bend <= fend) {
		/*
		* Case 2:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +-----------------+
		* fbno fend
		*
		* Case 3:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +--------------------------+
		* fbno fend
		*
		* Case 4:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +--------------------------+
		* fbno fend
		*
		* Case 5:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +-----------------------------------+
		* fbno fend
		*
		*/

		/*
		* The busy extent is fully covered by the extent we are
		* allocating, and can simply be removed from the rbtree.
		* However we cannot remove it from the immutable list
		* tracking busy extents in the transaction or CIL context,
		* so set the length to zero to mark it invalid.
		*
		* We also need to restart the busy extent search from the
		* tree root, because erasing the node can rearrange the
		* tree topology.
		*/
		rb_erase(&busyp->rb_node, &pag->pagb_tree);
		busyp->length = 0;
		return false;
		} else if (fend < bend) {
		/*
		* Case 6:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +---------+
		* fbno fend
		*
		* Case 7:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +------------------+
		* fbno fend
		*
		*/
		busyp->bno = fend;
		} else if (bbno < fbno) {
		/*
		* Case 8:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +-------------+
		* fbno fend
		*
		* Case 9:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +----------------------+
		* fbno fend
		*/
		busyp->length = fbno - busyp->bno;
		} else {
		ASSERT(0);
		}

		trace_xfs_alloc_busy_reuse(mp, pag->pag_agno, fbno, flen);
		return true;

		out_force_log:
		spin_unlock(&pag->pagb_lock);
		xfs_log_force(mp, XFS_LOG_SYNC);
		trace_xfs_alloc_busy_force(mp, pag->pag_agno, fbno, flen);
		spin_lock(&pag->pagb_lock);
		return false;
		}


		/*
		* For a given extent [fbno, flen], make sure we can reuse it safely.
		*/
		void
		xfs_alloc_busy_reuse(
		struct xfs_mount *mp,
		xfs_agnumber_t agno,
		xfs_agblock_t fbno,
		xfs_extlen_t flen,
		bool userdata)
		{
		struct xfs_perag *pag;
		struct rb_node *rbp;

		ASSERT(flen > 0);

		pag = xfs_perag_get(mp, agno);
		spin_lock(&pag->pagb_lock);
		restart:
		rbp = pag->pagb_tree.rb_node;
		while (rbp) {
		struct xfs_busy_extent *busyp =
		rb_entry(rbp, struct xfs_busy_extent, rb_node);
		xfs_agblock_t bbno = busyp->bno;
		xfs_agblock_t bend = bbno + busyp->length;

		if (fbno + flen <= bbno) {
		rbp = rbp->rb_left;
		continue;
		} else if (fbno >= bend) {
		rbp = rbp->rb_right;
		continue;
		}

		if (!xfs_alloc_busy_update_extent(mp, pag, busyp, fbno, flen,
		userdata))
		goto restart;
		}
		spin_unlock(&pag->pagb_lock);
		xfs_perag_put(pag);
		}

		/*
		* For a given extent [fbno, flen], search the busy extent list to find a
		* subset of the extent that is not busy. If *rlen is smaller than
		* args->minlen no suitable extent could be found, and the higher level
		* code needs to force out the log and retry the allocation.
		*/
		STATIC void
		xfs_alloc_busy_trim(
		struct xfs_alloc_arg *args,
		xfs_agblock_t bno,
		xfs_extlen_t len,
		xfs_agblock_t *rbno,
		xfs_extlen_t *rlen)
		{
		xfs_agblock_t fbno;
		xfs_extlen_t flen;
		struct rb_node *rbp;

		ASSERT(len > 0);

		spin_lock(&args->pag->pagb_lock);
		restart:
		fbno = bno;
		flen = len;
		rbp = args->pag->pagb_tree.rb_node;
		while (rbp && flen >= args->minlen) {
		struct xfs_busy_extent *busyp =
		rb_entry(rbp, struct xfs_busy_extent, rb_node);
		xfs_agblock_t fend = fbno + flen;
		xfs_agblock_t bbno = busyp->bno;
		xfs_agblock_t bend = bbno + busyp->length;

		if (fend <= bbno) {
		rbp = rbp->rb_left;
		continue;
		} else if (fbno >= bend) {
		rbp = rbp->rb_right;
		continue;
		}

		/*
		* If this is a metadata allocation, try to reuse the busy
		* extent instead of trimming the allocation.
		*/
		if (!args->userdata &&
		!(busyp->flags & XFS_ALLOC_BUSY_DISCARDED)) {
		if (!xfs_alloc_busy_update_extent(args->mp, args->pag,
		busyp, fbno, flen,
		false))
		goto restart;
		continue;
		}

		if (bbno <= fbno) {
		/* start overlap */

		/*
		* Case 1:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +---------+
		* fbno fend
		*
		* Case 2:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +-------------+
		* fbno fend
		*
		* Case 3:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +-------------+
		* fbno fend
		*
		* Case 4:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +-----------------+
		* fbno fend
		*
		* No unbusy region in extent, return failure.
		*/
		if (fend <= bend)
		goto fail;

		/*
		* Case 5:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +----------------------+
		* fbno fend
		*
		* Case 6:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +--------------------------+
		* fbno fend
		*
		* Needs to be trimmed to:
		* +-------+
		* fbno fend
		*/
		fbno = bend;
		} else if (bend >= fend) {
		/* end overlap */

		/*
		* Case 7:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +------------------+
		* fbno fend
		*
		* Case 8:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +--------------------------+
		* fbno fend
		*
		* Needs to be trimmed to:
		* +-------+
		* fbno fend
		*/
		fend = bbno;
		} else {
		/* middle overlap */

		/*
		* Case 9:
		* bbno bend
		* +BBBBBBBBBBBBBBBBB+
		* +-----------------------------------+
		* fbno fend
		*
		* Can be trimmed to:
		* +-------+ OR +-------+
		* fbno fend fbno fend
		*
		* Backward allocation leads to significant
		* fragmentation of directories, which degrades
		* directory performance, therefore we always want to
		* choose the option that produces forward allocation
		* patterns.
		* Preferring the lower bno extent will make the next
		* request use "fend" as the start of the next
		* allocation; if the segment is no longer busy at
		* that point, we'll get a contiguous allocation, but
		* even if it is still busy, we will get a forward
		* allocation.
		* We try to avoid choosing the segment at "bend",
		* because that can lead to the next allocation
		* taking the segment at "fbno", which would be a
		* backward allocation. We only use the segment at
		* "fbno" if it is much larger than the current
		* requested size, because in that case there's a
		* good chance subsequent allocations will be
		* contiguous.
		*/
		if (bbno - fbno >= args->maxlen) {
		/* left candidate fits perfect */
		fend = bbno;
		} else if (fend - bend >= args->maxlen * 4) {
		/* right candidate has enough free space */
		fbno = bend;
		} else if (bbno - fbno >= args->minlen) {
		/* left candidate fits minimum requirement */
		fend = bbno;
		} else {
		goto fail;
		}
		}

		flen = fend - fbno;
		}
		spin_unlock(&args->pag->pagb_lock);

		if (fbno != bno \|\| flen != len) {
		trace_xfs_alloc_busy_trim(args->mp, args->agno, bno, len,
		fbno, flen);
		}
		*rbno = fbno;
		*rlen = flen;
		return;
		fail:
		/*
		* Return a zero extent length as failure indications. All callers
		* re-check if the trimmed extent satisfies the minlen requirement.
		*/
		spin_unlock(&args->pag->pagb_lock);
		trace_xfs_alloc_busy_trim(args->mp, args->agno, bno, len, fbno, 0);
		*rbno = fbno;
		*rlen = 0;
		}

		static void
		xfs_alloc_busy_clear_one(
		struct xfs_mount *mp,
		struct xfs_perag *pag,
		struct xfs_busy_extent *busyp)
		{
		if (busyp->length) {
		trace_xfs_alloc_busy_clear(mp, busyp->agno, busyp->bno,
		busyp->length);
		rb_erase(&busyp->rb_node, &pag->pagb_tree);
		}

		list_del_init(&busyp->list);
		kmem_free(busyp);
		}

		/*
		* Remove all extents on the passed in list from the busy extents tree.
		* If do_discard is set skip extents that need to be discarded, and mark
		* these as undergoing a discard operation instead.
		*/
		void
		xfs_alloc_busy_clear(
		struct xfs_mount *mp,
		struct list_head *list,
		bool do_discard)
		{
		struct xfs_busy_extent busyp, n;
		struct xfs_perag *pag = NULL;
		xfs_agnumber_t agno = NULLAGNUMBER;

		list_for_each_entry_safe(busyp, n, list, list) {
		if (busyp->agno != agno) {
		if (pag) {
		spin_unlock(&pag->pagb_lock);
		xfs_perag_put(pag);
		}
		pag = xfs_perag_get(mp, busyp->agno);
		spin_lock(&pag->pagb_lock);
		agno = busyp->agno;
		}

		if (do_discard && busyp->length &&
		!(busyp->flags & XFS_ALLOC_BUSY_SKIP_DISCARD))
		busyp->flags = XFS_ALLOC_BUSY_DISCARDED;
		else
		xfs_alloc_busy_clear_one(mp, pag, busyp);
		}

		if (pag) {
		spin_unlock(&pag->pagb_lock);
		xfs_perag_put(pag);
		}
		}

		/*
		* Callback for list_sort to sort busy extents by the AG they reside in.
		*/
		int
		xfs_busy_extent_ag_cmp(
		void *priv,
		struct list_head *a,
		struct list_head *b)
		{
		return container_of(a, struct xfs_busy_extent, list)->agno -
		container_of(b, struct xfs_busy_extent, list)->agno;
		}

fs/xfs/xfs_alloc.h

+0 −28

Original line number	Diff line number	Diff line
		@@ -23,7 +23,6 @@ struct xfs_btree_cur;
		struct xfs_mount;
		struct xfs_perag;
		struct xfs_trans;
		struct xfs_busy_extent;

		extern struct workqueue_struct *xfs_alloc_wq;

		@@ -139,33 +138,6 @@ xfs_extlen_t
		xfs_alloc_longest_free_extent(struct xfs_mount *mp,
		struct xfs_perag *pag);

		#ifdef __KERNEL__
		void
		xfs_alloc_busy_insert(struct xfs_trans *tp, xfs_agnumber_t agno,
		xfs_agblock_t bno, xfs_extlen_t len, unsigned int flags);

		void
		xfs_alloc_busy_clear(struct xfs_mount mp, struct list_head list,
		bool do_discard);

		int
		xfs_alloc_busy_search(struct xfs_mount *mp, xfs_agnumber_t agno,
		xfs_agblock_t bno, xfs_extlen_t len);

		void
		xfs_alloc_busy_reuse(struct xfs_mount *mp, xfs_agnumber_t agno,
		xfs_agblock_t fbno, xfs_extlen_t flen, bool userdata);

		int
		xfs_busy_extent_ag_cmp(void priv, struct list_head a, struct list_head *b);

		static inline void xfs_alloc_busy_sort(struct list_head *list)
		{
		list_sort(NULL, list, xfs_busy_extent_ag_cmp);
		}

		#endif /* __KERNEL__ */

		/*
		* Compute and fill in value of m_ag_maxlevels.
		*/

fs/xfs/xfs_alloc_btree.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -31,6 +31,7 @@
		#include "xfs_inode.h"
		#include "xfs_btree.h"
		#include "xfs_alloc.h"
		#include "xfs_extent_busy.h"
		#include "xfs_error.h"
		#include "xfs_trace.h"

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