1 files changed, 407 insertions, 0 deletions
diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c
new file mode 100644
index 0000000000..2fc98d3137
--- /dev/null
+++ b/fs/xfs/xfs_filestream.c
@@ -0,0 +1,407 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2006-2007 Silicon Graphics, Inc.
+ * Copyright (c) 2014 Christoph Hellwig.
+ * All Rights Reserved.
+ */
+#include "xfs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_inode.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_util.h"
+#include "xfs_alloc.h"
+#include "xfs_mru_cache.h"
+#include "xfs_trace.h"
+#include "xfs_ag.h"
+#include "xfs_ag_resv.h"
+#include "xfs_trans.h"
+#include "xfs_filestream.h"
+
+struct xfs_fstrm_item {
+	struct xfs_mru_cache_elem	mru;
+	struct xfs_perag		*pag; /* AG in use for this directory */
+};
+
+enum xfs_fstrm_alloc {
+	XFS_PICK_USERDATA = 1,
+	XFS_PICK_LOWSPACE = 2,
+};
+
+static void
+xfs_fstrm_free_func(
+	void			*data,
+	struct xfs_mru_cache_elem *mru)
+{
+	struct xfs_fstrm_item	*item =
+		container_of(mru, struct xfs_fstrm_item, mru);
+	struct xfs_perag	*pag = item->pag;
+
+	trace_xfs_filestream_free(pag, mru->key);
+	atomic_dec(&pag->pagf_fstrms);
+	xfs_perag_rele(pag);
+
+	kmem_free(item);
+}
+
+/*
+ * Scan the AGs starting at start_agno looking for an AG that isn't in use and
+ * has at least minlen blocks free. If no AG is found to match the allocation
+ * requirements, pick the AG with the most free space in it.
+ */
+static int
+xfs_filestream_pick_ag(
+	struct xfs_alloc_arg	*args,
+	xfs_ino_t		pino,
+	xfs_agnumber_t		start_agno,
+	int			flags,
+	xfs_extlen_t		*longest)
+{
+	struct xfs_mount	*mp = args->mp;
+	struct xfs_perag	*pag;
+	struct xfs_perag	*max_pag = NULL;
+	xfs_extlen_t		minlen = *longest;
+	xfs_extlen_t		free = 0, minfree, maxfree = 0;
+	xfs_agnumber_t		agno;
+	bool			first_pass = true;
+	int			err;
+
+	/* 2% of an AG's blocks must be free for it to be chosen. */
+	minfree = mp->m_sb.sb_agblocks / 50;
+
+restart:
+	for_each_perag_wrap(mp, start_agno, agno, pag) {
+		trace_xfs_filestream_scan(pag, pino);
+		*longest = 0;
+		err = xfs_bmap_longest_free_extent(pag, NULL, longest);
+		if (err) {
+			if (err != -EAGAIN)
+				break;
+			/* Couldn't lock the AGF, skip this AG. */
+			err = 0;
+			continue;
+		}
+
+		/* Keep track of the AG with the most free blocks. */
+		if (pag->pagf_freeblks > maxfree) {
+			maxfree = pag->pagf_freeblks;
+			if (max_pag)
+				xfs_perag_rele(max_pag);
+			atomic_inc(&pag->pag_active_ref);
+			max_pag = pag;
+		}
+
+		/*
+		 * The AG reference count does two things: it enforces mutual
+		 * exclusion when examining the suitability of an AG in this
+		 * loop, and it guards against two filestreams being established
+		 * in the same AG as each other.
+		 */
+		if (atomic_inc_return(&pag->pagf_fstrms) <= 1) {
+			if (((minlen && *longest >= minlen) ||
+			     (!minlen && pag->pagf_freeblks >= minfree)) &&
+			    (!xfs_perag_prefers_metadata(pag) ||
+			     !(flags & XFS_PICK_USERDATA) ||
+			     (flags & XFS_PICK_LOWSPACE))) {
+				/* Break out, retaining the reference on the AG. */
+				free = pag->pagf_freeblks;
+				break;
+			}
+		}
+
+		/* Drop the reference on this AG, it's not usable. */
+		atomic_dec(&pag->pagf_fstrms);
+	}
+
+	if (err) {
+		xfs_perag_rele(pag);
+		if (max_pag)
+			xfs_perag_rele(max_pag);
+		return err;
+	}
+
+	if (!pag) {
+		/*
+		 * Allow a second pass to give xfs_bmap_longest_free_extent()
+		 * another attempt at locking AGFs that it might have skipped
+		 * over before we fail.
+		 */
+		if (first_pass) {
+			first_pass = false;
+			goto restart;
+		}
+
+		/*
+		 * We must be low on data space, so run a final lowspace
+		 * optimised selection pass if we haven't already.
+		 */
+		if (!(flags & XFS_PICK_LOWSPACE)) {
+			flags |= XFS_PICK_LOWSPACE;
+			goto restart;
+		}
+
+		/*
+		 * No unassociated AGs are available, so select the AG with the
+		 * most free space, regardless of whether it's already in use by
+		 * another filestream. It none suit, just use whatever AG we can
+		 * grab.
+		 */
+		if (!max_pag) {
+			for_each_perag_wrap(args->mp, 0, start_agno, args->pag)
+				break;
+			atomic_inc(&args->pag->pagf_fstrms);
+			*longest = 0;
+		} else {
+			pag = max_pag;
+			free = maxfree;
+			atomic_inc(&pag->pagf_fstrms);
+		}
+	} else if (max_pag) {
+		xfs_perag_rele(max_pag);
+	}
+
+	trace_xfs_filestream_pick(pag, pino, free);
+	args->pag = pag;
+	return 0;
+
+}
+
+static struct xfs_inode *
+xfs_filestream_get_parent(
+	struct xfs_inode	*ip)
+{
+	struct inode		*inode = VFS_I(ip), *dir = NULL;
+	struct dentry		*dentry, *parent;
+
+	dentry = d_find_alias(inode);
+	if (!dentry)
+		goto out;
+
+	parent = dget_parent(dentry);
+	if (!parent)
+		goto out_dput;
+
+	dir = igrab(d_inode(parent));
+	dput(parent);
+
+out_dput:
+	dput(dentry);
+out:
+	return dir ? XFS_I(dir) : NULL;
+}
+
+/*
+ * Lookup the mru cache for an existing association. If one exists and we can
+ * use it, return with an active perag reference indicating that the allocation
+ * will proceed with that association.
+ *
+ * If we have no association, or we cannot use the current one and have to
+ * destroy it, return with longest = 0 to tell the caller to create a new
+ * association.
+ */
+static int
+xfs_filestream_lookup_association(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args,
+	xfs_ino_t		pino,
+	xfs_extlen_t		*longest)
+{
+	struct xfs_mount	*mp = args->mp;
+	struct xfs_perag	*pag;
+	struct xfs_mru_cache_elem *mru;
+	int			error = 0;
+
+	*longest = 0;
+	mru = xfs_mru_cache_lookup(mp->m_filestream, pino);
+	if (!mru)
+		return 0;
+	/*
+	 * Grab the pag and take an extra active reference for the caller whilst
+	 * the mru item cannot go away. This means we'll pin the perag with
+	 * the reference we get here even if the filestreams association is torn
+	 * down immediately after we mark the lookup as done.
+	 */
+	pag = container_of(mru, struct xfs_fstrm_item, mru)->pag;
+	atomic_inc(&pag->pag_active_ref);
+	xfs_mru_cache_done(mp->m_filestream);
+
+	trace_xfs_filestream_lookup(pag, ap->ip->i_ino);
+
+	ap->blkno = XFS_AGB_TO_FSB(args->mp, pag->pag_agno, 0);
+	xfs_bmap_adjacent(ap);
+
+	/*
+	 * If there is very little free space before we start a filestreams
+	 * allocation, we're almost guaranteed to fail to find a large enough
+	 * free space available so just use the cached AG.
+	 */
+	if (ap->tp->t_flags & XFS_TRANS_LOWMODE) {
+		*longest = 1;
+		goto out_done;
+	}
+
+	error = xfs_bmap_longest_free_extent(pag, args->tp, longest);
+	if (error == -EAGAIN)
+		error = 0;
+	if (error || *longest < args->maxlen) {
+		/* We aren't going to use this perag */
+		*longest = 0;
+		xfs_perag_rele(pag);
+		return error;
+	}
+
+out_done:
+	args->pag = pag;
+	return 0;
+}
+
+static int
+xfs_filestream_create_association(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args,
+	xfs_ino_t		pino,
+	xfs_extlen_t		*longest)
+{
+	struct xfs_mount	*mp = args->mp;
+	struct xfs_mru_cache_elem *mru;
+	struct xfs_fstrm_item	*item;
+	xfs_agnumber_t		agno = XFS_INO_TO_AGNO(mp, pino);
+	int			flags = 0;
+	int			error;
+
+	/* Changing parent AG association now, so remove the existing one. */
+	mru = xfs_mru_cache_remove(mp->m_filestream, pino);
+	if (mru) {
+		struct xfs_fstrm_item *item =
+			container_of(mru, struct xfs_fstrm_item, mru);
+
+		agno = (item->pag->pag_agno + 1) % mp->m_sb.sb_agcount;
+		xfs_fstrm_free_func(mp, mru);
+	} else if (xfs_is_inode32(mp)) {
+		xfs_agnumber_t	 rotorstep = xfs_rotorstep;
+
+		agno = (mp->m_agfrotor / rotorstep) % mp->m_sb.sb_agcount;
+		mp->m_agfrotor = (mp->m_agfrotor + 1) %
+				 (mp->m_sb.sb_agcount * rotorstep);
+	}
+
+	ap->blkno = XFS_AGB_TO_FSB(args->mp, agno, 0);
+	xfs_bmap_adjacent(ap);
+
+	if (ap->datatype & XFS_ALLOC_USERDATA)
+		flags |= XFS_PICK_USERDATA;
+	if (ap->tp->t_flags & XFS_TRANS_LOWMODE)
+		flags |= XFS_PICK_LOWSPACE;
+
+	*longest = ap->length;
+	error = xfs_filestream_pick_ag(args, pino, agno, flags, longest);
+	if (error)
+		return error;
+
+	/*
+	 * We are going to use this perag now, so create an assoication for it.
+	 * xfs_filestream_pick_ag() has already bumped the perag fstrms counter
+	 * for us, so all we need to do here is take another active reference to
+	 * the perag for the cached association.
+	 *
+	 * If we fail to store the association, we need to drop the fstrms
+	 * counter as well as drop the perag reference we take here for the
+	 * item. We do not need to return an error for this failure - as long as
+	 * we return a referenced AG, the allocation can still go ahead just
+	 * fine.
+	 */
+	item = kmem_alloc(sizeof(*item), KM_MAYFAIL);
+	if (!item)
+		goto out_put_fstrms;
+
+	atomic_inc(&args->pag->pag_active_ref);
+	item->pag = args->pag;
+	error = xfs_mru_cache_insert(mp->m_filestream, pino, &item->mru);
+	if (error)
+		goto out_free_item;
+	return 0;
+
+out_free_item:
+	xfs_perag_rele(item->pag);
+	kmem_free(item);
+out_put_fstrms:
+	atomic_dec(&args->pag->pagf_fstrms);
+	return 0;
+}
+
+/*
+ * Search for an allocation group with a single extent large enough for
+ * the request. First we look for an existing association and use that if it
+ * is found. Otherwise, we create a new association by selecting an AG that fits
+ * the allocation criteria.
+ *
+ * We return with a referenced perag in args->pag to indicate which AG we are
+ * allocating into or an error with no references held.
+ */
+int
+xfs_filestream_select_ag(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args,
+	xfs_extlen_t		*longest)
+{
+	struct xfs_mount	*mp = args->mp;
+	struct xfs_inode	*pip;
+	xfs_ino_t		ino = 0;
+	int			error = 0;
+
+	*longest = 0;
+	args->total = ap->total;
+	pip = xfs_filestream_get_parent(ap->ip);
+	if (pip) {
+		ino = pip->i_ino;
+		error = xfs_filestream_lookup_association(ap, args, ino,
+				longest);
+		xfs_irele(pip);
+		if (error)
+			return error;
+		if (*longest >= args->maxlen)
+			goto out_select;
+		if (ap->tp->t_flags & XFS_TRANS_LOWMODE)
+			goto out_select;
+	}
+
+	error = xfs_filestream_create_association(ap, args, ino, longest);
+	if (error)
+		return error;
+
+out_select:
+	ap->blkno = XFS_AGB_TO_FSB(mp, args->pag->pag_agno, 0);
+	return 0;
+}
+
+void
+xfs_filestream_deassociate(
+	struct xfs_inode	*ip)
+{
+	xfs_mru_cache_delete(ip->i_mount->m_filestream, ip->i_ino);
+}
+
+int
+xfs_filestream_mount(
+	xfs_mount_t	*mp)
+{
+	/*
+	 * The filestream timer tunable is currently fixed within the range of
+	 * one second to four minutes, with five seconds being the default.  The
+	 * group count is somewhat arbitrary, but it'd be nice to adhere to the
+	 * timer tunable to within about 10 percent.  This requires at least 10
+	 * groups.
+	 */
+	return xfs_mru_cache_create(&mp->m_filestream, mp,
+			xfs_fstrm_centisecs * 10, 10, xfs_fstrm_free_func);
+}
+
+void
+xfs_filestream_unmount(
+	xfs_mount_t	*mp)
+{
+	xfs_mru_cache_destroy(mp->m_filestream);
+}