xfs: remove "no-allocation" reservations for file creations

If we create a new file we will need an inode, and usually some metadata
in the parent direction.  Aiming for everything to go well despite the
lack of a reservation leads to dirty transactions cancelled under a heavy
create/delete load.  This patch removes those nospace transactions, which
will lead to slightly earlier ENOSPC on some workloads, but instead
prevent file system shutdowns due to cancelling dirty transactions for
others.

A customer could observe assertations failures and shutdowns due to
cancelation of dirty transactions during heavy NFS workloads as shown
below:

2017-05-30 21:17:06 kernel: WARNING: [ 2670.728125] XFS: Assertion failed: error != -ENOSPC, file: fs/xfs/xfs_inode.c, line: 1262

2017-05-30 21:17:06 kernel: WARNING: [ 2670.728222] Call Trace:
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728246]  [<ffffffff81795daf>] dump_stack+0x63/0x81
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728262]  [<ffffffff810a1a5a>] warn_slowpath_common+0x8a/0xc0
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728264]  [<ffffffff810a1b8a>] warn_slowpath_null+0x1a/0x20
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728285]  [<ffffffffa01bf403>] asswarn+0x33/0x40 [xfs]
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728308]  [<ffffffffa01bb07e>] xfs_create+0x7be/0x7d0 [xfs]
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728329]  [<ffffffffa01b6ffb>] xfs_generic_create+0x1fb/0x2e0 [xfs]
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728348]  [<ffffffffa01b7114>] xfs_vn_mknod+0x14/0x20 [xfs]
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728366]  [<ffffffffa01b7153>] xfs_vn_create+0x13/0x20 [xfs]
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728380]  [<ffffffff81231de5>] vfs_create+0xd5/0x140
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728390]  [<ffffffffa045ddb9>] do_nfsd_create+0x499/0x610 [nfsd]
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728396]  [<ffffffffa0465fa5>] nfsd3_proc_create+0x135/0x210 [nfsd]
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728401]  [<ffffffffa04561e3>] nfsd_dispatch+0xc3/0x210 [nfsd]
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728416]  [<ffffffffa03bfa43>] svc_process_common+0x453/0x6f0 [sunrpc]
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728423]  [<ffffffffa03bfdf3>] svc_process+0x113/0x1f0 [sunrpc]
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728427]  [<ffffffffa0455bcf>] nfsd+0x10f/0x180 [nfsd]
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728432]  [<ffffffffa0455ac0>] ? nfsd_destroy+0x80/0x80 [nfsd]
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728438]  [<ffffffff810c0d58>] kthread+0xd8/0xf0
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728441]  [<ffffffff810c0c80>] ? kthread_create_on_node+0x1b0/0x1b0
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728451]  [<ffffffff8179d962>] ret_from_fork+0x42/0x70
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728453]  [<ffffffff810c0c80>] ? kthread_create_on_node+0x1b0/0x1b0
2017-05-30 21:17:06 kernel: WARNING: [ 2670.728454] ---[ end trace f9822c842fec81d4 ]---

2017-05-30 21:17:06 kernel: ALERT: [ 2670.728477] XFS (sdb): Internal error xfs_trans_cancel at line 983 of file fs/xfs/xfs_trans.c.  Caller xfs_create+0x4ee/0x7d0 [xfs]

2017-05-30 21:17:06 kernel: ALERT: [ 2670.728684] XFS (sdb): Corruption of in-memory data detected. Shutting down filesystem
2017-05-30 21:17:06 kernel: ALERT: [ 2670.728685] XFS (sdb): Please umount the filesystem and rectify the problem(s)
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_ialloc.c

@@ -920,8 +920,7 @@ STATIC xfs_agnumber_t
 xfs_ialloc_ag_select(
 	xfs_trans_t	*tp,		/* transaction pointer */
 	xfs_ino_t	parent,		/* parent directory inode number */
-	umode_t		mode,		/* bits set to indicate file type */
-	int		okalloc)	/* ok to allocate more space */
+	umode_t		mode)		/* bits set to indicate file type */
 {
 	xfs_agnumber_t	agcount;	/* number of ag's in the filesystem */
 	xfs_agnumber_t	agno;		/* current ag number */
@@ -978,9 +977,6 @@ xfs_ialloc_ag_select(
 			return agno;
 		}
 
-		if (!okalloc)
-			goto nextag;
-
 		if (!pag->pagf_init) {
 			error = xfs_alloc_pagf_init(mp, tp, agno, flags);
 			if (error)
@@ -1680,7 +1676,6 @@ xfs_dialloc(
 	struct xfs_trans	*tp,
 	xfs_ino_t		parent,
 	umode_t			mode,
-	int			okalloc,
 	struct xfs_buf		**IO_agbp,
 	xfs_ino_t		*inop)
 {
@@ -1692,6 +1687,7 @@ xfs_dialloc(
 	int			noroom = 0;
 	xfs_agnumber_t		start_agno;
 	struct xfs_perag	*pag;
+	int			okalloc = 1;
 
 	if (*IO_agbp) {
 		/*
@@ -1707,7 +1703,7 @@ xfs_dialloc(
 	 * We do not have an agbp, so select an initial allocation
 	 * group for inode allocation.
 	 */
-	start_agno = xfs_ialloc_ag_select(tp, parent, mode, okalloc);
+	start_agno = xfs_ialloc_ag_select(tp, parent, mode);
 	if (start_agno == NULLAGNUMBER) {
 		*inop = NULLFSINO;
 		return 0;

fs/xfs/libxfs/xfs_ialloc.h

@@ -81,7 +81,6 @@ xfs_dialloc(
 	struct xfs_trans *tp,		/* transaction pointer */
 	xfs_ino_t	parent,		/* parent inode (directory) */
 	umode_t		mode,		/* mode bits for new inode */
-	int		okalloc,	/* ok to allocate more space */
 	struct xfs_buf	**agbp,		/* buf for a.g. inode header */
 	xfs_ino_t	*inop);		/* inode number allocated */
 

fs/xfs/xfs_inode.c

@@ -749,7 +749,6 @@ xfs_ialloc(
 	xfs_nlink_t	nlink,
 	dev_t		rdev,
 	prid_t		prid,
-	int		okalloc,
 	xfs_buf_t	**ialloc_context,
 	xfs_inode_t	**ipp)
 {
@@ -765,7 +764,7 @@ xfs_ialloc(
 	 * Call the space management code to pick
 	 * the on-disk inode to be allocated.
 	 */
-	error = xfs_dialloc(tp, pip ? pip->i_ino : 0, mode, okalloc,
+	error = xfs_dialloc(tp, pip ? pip->i_ino : 0, mode,
 			    ialloc_context, &ino);
 	if (error)
 		return error;
@@ -957,7 +956,6 @@ xfs_dir_ialloc(
 	xfs_nlink_t	nlink,
 	dev_t		rdev,
 	prid_t		prid,		/* project id */
-	int		okalloc,	/* ok to allocate new space */
 	xfs_inode_t	**ipp,		/* pointer to inode; it will be
 					   locked. */
 	int		*committed)
@@ -988,8 +986,8 @@ xfs_dir_ialloc(
 	 * transaction commit so that no other process can steal
 	 * the inode(s) that we've just allocated.
 	 */
-	code = xfs_ialloc(tp, dp, mode, nlink, rdev, prid, okalloc,
-			  &ialloc_context, &ip);
+	code = xfs_ialloc(tp, dp, mode, nlink, rdev, prid, &ialloc_context,
+			&ip);
 
 	/*
 	 * Return an error if we were unable to allocate a new inode.
@@ -1061,7 +1059,7 @@ xfs_dir_ialloc(
 		 * this call should always succeed.
 		 */
 		code = xfs_ialloc(tp, dp, mode, nlink, rdev, prid,
-				  okalloc, &ialloc_context, &ip);
+				  &ialloc_context, &ip);
 
 		/*
 		 * If we get an error at this point, return to the caller
@@ -1182,11 +1180,6 @@ xfs_create(
 		xfs_flush_inodes(mp);
 		error = xfs_trans_alloc(mp, tres, resblks, 0, 0, &tp);
 	}
-	if (error == -ENOSPC) {
-		/* No space at all so try a "no-allocation" reservation */
-		resblks = 0;
-		error = xfs_trans_alloc(mp, tres, 0, 0, 0, &tp);
-	}
 	if (error)
 		goto out_release_inode;
 
@@ -1203,19 +1196,13 @@ xfs_create(
 	if (error)
 		goto out_trans_cancel;
 
-	if (!resblks) {
-		error = xfs_dir_canenter(tp, dp, name);
-		if (error)
-			goto out_trans_cancel;
-	}
-
 	/*
 	 * A newly created regular or special file just has one directory
 	 * entry pointing to them, but a directory also the "." entry
 	 * pointing to itself.
 	 */
-	error = xfs_dir_ialloc(&tp, dp, mode, is_dir ? 2 : 1, rdev,
-			       prid, resblks > 0, &ip, NULL);
+	error = xfs_dir_ialloc(&tp, dp, mode, is_dir ? 2 : 1, rdev, prid, &ip,
+			NULL);
 	if (error)
 		goto out_trans_cancel;
 
@@ -1340,11 +1327,6 @@ xfs_create_tmpfile(
 	tres = &M_RES(mp)->tr_create_tmpfile;
 
 	error = xfs_trans_alloc(mp, tres, resblks, 0, 0, &tp);
-	if (error == -ENOSPC) {
-		/* No space at all so try a "no-allocation" reservation */
-		resblks = 0;
-		error = xfs_trans_alloc(mp, tres, 0, 0, 0, &tp);
-	}
 	if (error)
 		goto out_release_inode;
 
@@ -1353,8 +1335,7 @@ xfs_create_tmpfile(
 	if (error)
 		goto out_trans_cancel;
 
-	error = xfs_dir_ialloc(&tp, dp, mode, 1, 0,
-				prid, resblks > 0, &ip, NULL);
+	error = xfs_dir_ialloc(&tp, dp, mode, 1, 0, prid, &ip, NULL);
 	if (error)
 		goto out_trans_cancel;
 

fs/xfs/xfs_inode.h

@@ -428,7 +428,7 @@ xfs_extlen_t	xfs_get_extsz_hint(struct xfs_inode *ip);
 xfs_extlen_t	xfs_get_cowextsz_hint(struct xfs_inode *ip);
 
 int		xfs_dir_ialloc(struct xfs_trans **, struct xfs_inode *, umode_t,
-			       xfs_nlink_t, dev_t, prid_t, int,
+			       xfs_nlink_t, dev_t, prid_t,
 			       struct xfs_inode **, int *);
 
 /* from xfs_file.c */

fs/xfs/xfs_qm.c

@@ -793,8 +793,8 @@ xfs_qm_qino_alloc(
 		return error;
 
 	if (need_alloc) {
-		error = xfs_dir_ialloc(&tp, NULL, S_IFREG, 1, 0, 0, 1, ip,
-								&committed);
+		error = xfs_dir_ialloc(&tp, NULL, S_IFREG, 1, 0, 0, ip,
+				&committed);
 		if (error) {
 			xfs_trans_cancel(tp);
 			return error;

fs/xfs/xfs_symlink.c

@@ -232,11 +232,6 @@ xfs_symlink(
 	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);
-	if (error == -ENOSPC && fs_blocks == 0) {
-		resblks = 0;
-		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_symlink, 0, 0, 0,
-				&tp);
-	}
 	if (error)
 		goto out_release_inode;
 
@@ -259,14 +254,6 @@ xfs_symlink(
 	if (error)
 		goto out_trans_cancel;
 
-	/*
-	 * Check for ability to enter directory entry, if no space reserved.
-	 */
-	if (!resblks) {
-		error = xfs_dir_canenter(tp, dp, link_name);
-		if (error)
-			goto out_trans_cancel;
-	}
 	/*
 	 * Initialize the bmap freelist prior to calling either
 	 * bmapi or the directory create code.
@@ -277,7 +264,7 @@ xfs_symlink(
 	 * Allocate an inode for the symlink.
 	 */
 	error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
-			       prid, resblks > 0, &ip, NULL);
+			       prid, &ip, NULL);
 	if (error)
 		goto out_trans_cancel;