4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christoph Hellwig <h...@lst.de>

commit 255c516278175a6dc7037d1406307f35237d8688 upstream.

We can't just set minleft to 0 when we're low on space - that's exactly
what we need minleft for: to protect space in the AG for btree block
allocations when we are low on free space.

Signed-off-by: Christoph Hellwig <h...@lst.de>
Reviewed-by: Brian Foster <bfos...@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.w...@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 fs/xfs/libxfs/xfs_alloc.c      |   24 +++++++-----------------
 fs/xfs/libxfs/xfs_bmap.c       |    3 ---
 fs/xfs/libxfs/xfs_bmap_btree.c |    3 +--
 3 files changed, 8 insertions(+), 22 deletions(-)

--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2635,12 +2635,10 @@ xfs_alloc_vextent(
        xfs_agblock_t   agsize; /* allocation group size */
        int             error;
        int             flags;  /* XFS_ALLOC_FLAG_... locking flags */
-       xfs_extlen_t    minleft;/* minimum left value, temp copy */
        xfs_mount_t     *mp;    /* mount structure pointer */
        xfs_agnumber_t  sagno;  /* starting allocation group number */
        xfs_alloctype_t type;   /* input allocation type */
        int             bump_rotor = 0;
-       int             no_min = 0;
        xfs_agnumber_t  rotorstep = xfs_rotorstep; /* inode32 agf stepper */
 
        mp = args->mp;
@@ -2669,7 +2667,6 @@ xfs_alloc_vextent(
                trace_xfs_alloc_vextent_badargs(args);
                return 0;
        }
-       minleft = args->minleft;
 
        switch (type) {
        case XFS_ALLOCTYPE_THIS_AG:
@@ -2680,9 +2677,7 @@ xfs_alloc_vextent(
                 */
                args->agno = XFS_FSB_TO_AGNO(mp, args->fsbno);
                args->pag = xfs_perag_get(mp, args->agno);
-               args->minleft = 0;
                error = xfs_alloc_fix_freelist(args, 0);
-               args->minleft = minleft;
                if (error) {
                        trace_xfs_alloc_vextent_nofix(args);
                        goto error0;
@@ -2747,9 +2742,7 @@ xfs_alloc_vextent(
                 */
                for (;;) {
                        args->pag = xfs_perag_get(mp, args->agno);
-                       if (no_min) args->minleft = 0;
                        error = xfs_alloc_fix_freelist(args, flags);
-                       args->minleft = minleft;
                        if (error) {
                                trace_xfs_alloc_vextent_nofix(args);
                                goto error0;
@@ -2789,20 +2782,17 @@ xfs_alloc_vextent(
                         * or switch to non-trylock mode.
                         */
                        if (args->agno == sagno) {
-                               if (no_min == 1) {
+                               if (flags == 0) {
                                        args->agbno = NULLAGBLOCK;
                                        trace_xfs_alloc_vextent_allfailed(args);
                                        break;
                                }
-                               if (flags == 0) {
-                                       no_min = 1;
-                               } else {
-                                       flags = 0;
-                                       if (type == XFS_ALLOCTYPE_START_BNO) {
-                                               args->agbno = 
XFS_FSB_TO_AGBNO(mp,
-                                                       args->fsbno);
-                                               args->type = 
XFS_ALLOCTYPE_NEAR_BNO;
-                                       }
+
+                               flags = 0;
+                               if (type == XFS_ALLOCTYPE_START_BNO) {
+                                       args->agbno = XFS_FSB_TO_AGBNO(mp,
+                                               args->fsbno);
+                                       args->type = XFS_ALLOCTYPE_NEAR_BNO;
                                }
                        }
                        xfs_perag_put(args->pag);
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -3903,7 +3903,6 @@ xfs_bmap_btalloc(
                args.fsbno = 0;
                args.type = XFS_ALLOCTYPE_FIRST_AG;
                args.total = ap->minlen;
-               args.minleft = 0;
                if ((error = xfs_alloc_vextent(&args)))
                        return error;
                ap->dfops->dop_low = true;
@@ -4437,8 +4436,6 @@ xfs_bmapi_allocate(
        if (error)
                return error;
 
-       if (bma->dfops->dop_low)
-               bma->minleft = 0;
        if (bma->cur)
                bma->cur->bc_private.b.firstblock = *bma->firstblock;
        if (bma->blkno == NULLFSBLOCK)
--- a/fs/xfs/libxfs/xfs_bmap_btree.c
+++ b/fs/xfs/libxfs/xfs_bmap_btree.c
@@ -502,12 +502,11 @@ try_another_ag:
        if (args.fsbno == NULLFSBLOCK && args.minleft) {
                /*
                 * Could not find an AG with enough free space to satisfy
-                * a full btree split.  Try again without minleft and if
+                * a full btree split.  Try again and if
                 * successful activate the lowspace algorithm.
                 */
                args.fsbno = 0;
                args.type = XFS_ALLOCTYPE_FIRST_AG;
-               args.minleft = 0;
                error = xfs_alloc_vextent(&args);
                if (error)
                        goto error0;


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