xfs: refactor inode creation transaction/inode/quota allocation idiom

For file creation, create a new helper xfs_trans_alloc_icreate that
allocates a transaction and reserves the appropriate amount of quota
against that transction.  Replace all the open-coded idioms with a
single call to this helper so that we can contain the retry loops in the
next patchset.

This changes the locking behavior for non-tempfile creation slightly, in
that we now make the quota reservation without holding the directory
ILOCK.  While the dquots chosen for inode creation are based on the
directory state at a given point in time, the directory ILOCK was
released as soon as the dquot references are picked up.  Hence it was
never necessary to hold the directory ILOCK for the quota reservation.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/xfs_inode.c

@@ -1022,25 +1022,20 @@ xfs_create(
 	 * the case we'll drop the one we have and get a more
 	 * appropriate transaction later.
 	 */
-	error = xfs_trans_alloc(mp, tres, resblks, 0, 0, &tp);
+	error = xfs_trans_alloc_icreate(mp, tres, udqp, gdqp, pdqp, resblks,
+			&tp);
 	if (error == -ENOSPC) {
 		/* flush outstanding delalloc blocks and retry */
 		xfs_flush_inodes(mp);
-		error = xfs_trans_alloc(mp, tres, resblks, 0, 0, &tp);
+		error = xfs_trans_alloc_icreate(mp, tres, udqp, gdqp, pdqp,
+				resblks, &tp);
 	}
 	if (error)
-		goto out_release_inode;
+		goto out_release_dquots;
 
 	xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 	unlock_dp_on_error = true;
 
-	/*
-	 * Reserve disk quota and the inode.
-	 */
-	error = xfs_trans_reserve_quota_icreate(tp, udqp, gdqp, pdqp, resblks);
-	if (error)
-		goto out_trans_cancel;
-
 	error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK,
 			XFS_IEXT_DIR_MANIP_CNT(mp));
 	if (error)
@@ -1120,7 +1115,7 @@ xfs_create(
 		xfs_finish_inode_setup(ip);
 		xfs_irele(ip);
 	}
-
+ out_release_dquots:
 	xfs_qm_dqrele(udqp);
 	xfs_qm_dqrele(gdqp);
 	xfs_qm_dqrele(pdqp);
@@ -1164,13 +1159,10 @@ xfs_create_tmpfile(
 	resblks = XFS_IALLOC_SPACE_RES(mp);
 	tres = &M_RES(mp)->tr_create_tmpfile;
 
-	error = xfs_trans_alloc(mp, tres, resblks, 0, 0, &tp);
-	if (error)
-		goto out_release_inode;
-
-	error = xfs_trans_reserve_quota_icreate(tp, udqp, gdqp, pdqp, resblks);
+	error = xfs_trans_alloc_icreate(mp, tres, udqp, gdqp, pdqp, resblks,
+			&tp);
 	if (error)
-		goto out_trans_cancel;
+		goto out_release_dquots;
 
 	error = xfs_dir_ialloc(&tp, dp, mode, 0, 0, prid, &ip);
 	if (error)
@@ -1213,7 +1205,7 @@ xfs_create_tmpfile(
 		xfs_finish_inode_setup(ip);
 		xfs_irele(ip);
 	}
-
+ out_release_dquots:
 	xfs_qm_dqrele(udqp);
 	xfs_qm_dqrele(gdqp);
 	xfs_qm_dqrele(pdqp);

fs/xfs/xfs_symlink.c

@@ -197,9 +197,10 @@ xfs_symlink(
 		fs_blocks = xfs_symlink_blocks(mp, pathlen);
 	resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
 
-	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_symlink, resblks, 0, 0, &tp);
+	error = xfs_trans_alloc_icreate(mp, &M_RES(mp)->tr_symlink, udqp, gdqp,
+			pdqp, resblks, &tp);
 	if (error)
-		goto out_release_inode;
+		goto out_release_dquots;
 
 	xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 	unlock_dp_on_error = true;
@@ -212,13 +213,6 @@ xfs_symlink(
 		goto out_trans_cancel;
 	}
 
-	/*
-	 * Reserve disk quota : blocks and inode.
-	 */
-	error = xfs_trans_reserve_quota_icreate(tp, udqp, gdqp, pdqp, resblks);
-	if (error)
-		goto out_trans_cancel;
-
 	error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK,
 			XFS_IEXT_DIR_MANIP_CNT(mp));
 	if (error)
@@ -347,7 +341,7 @@ xfs_symlink(
 		xfs_finish_inode_setup(ip);
 		xfs_irele(ip);
 	}
-
+out_release_dquots:
 	xfs_qm_dqrele(udqp);
 	xfs_qm_dqrele(gdqp);
 	xfs_qm_dqrele(pdqp);

fs/xfs/xfs_trans.c

@@ -21,6 +21,8 @@
 #include "xfs_error.h"
 #include "xfs_defer.h"
 #include "xfs_inode.h"
+#include "xfs_dquot_item.h"
+#include "xfs_dquot.h"
 
 kmem_zone_t	*xfs_trans_zone;
 
@@ -1074,3 +1076,34 @@ xfs_trans_alloc_inode(
 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 	return error;
 }
+
+/*
+ * Allocate an transaction in preparation for inode creation by reserving quota
+ * against the given dquots.  Callers are not required to hold any inode locks.
+ */
+int
+xfs_trans_alloc_icreate(
+	struct xfs_mount	*mp,
+	struct xfs_trans_res	*resv,
+	struct xfs_dquot	*udqp,
+	struct xfs_dquot	*gdqp,
+	struct xfs_dquot	*pdqp,
+	unsigned int		dblocks,
+	struct xfs_trans	**tpp)
+{
+	struct xfs_trans	*tp;
+	int			error;
+
+	error = xfs_trans_alloc(mp, resv, dblocks, 0, 0, &tp);
+	if (error)
+		return error;
+
+	error = xfs_trans_reserve_quota_icreate(tp, udqp, gdqp, pdqp, dblocks);
+	if (error) {
+		xfs_trans_cancel(tp);
+		return error;
+	}
+
+	*tpp = tp;
+	return 0;
+}

fs/xfs/xfs_trans.h

@@ -268,8 +268,14 @@ xfs_trans_item_relog(
 	return lip->li_ops->iop_relog(lip, tp);
 }
 
+struct xfs_dquot;
+
 int xfs_trans_alloc_inode(struct xfs_inode *ip, struct xfs_trans_res *resv,
 		unsigned int dblocks, unsigned int rblocks, bool force,
 		struct xfs_trans **tpp);
+int xfs_trans_alloc_icreate(struct xfs_mount *mp, struct xfs_trans_res *resv,
+		struct xfs_dquot *udqp, struct xfs_dquot *gdqp,
+		struct xfs_dquot *pdqp, unsigned int dblocks,
+		struct xfs_trans **tpp);
 
 #endif	/* __XFS_TRANS_H__ */