xfs: move the minimum agno checks into xfs_alloc_vextent_check_args

All of the allocation functions now extract the minimum allowed AG
from the transaction and then use it in some way. The allocation
functions that are restricted to a single AG all check if the
AG requested can be allocated from and return an error if so. These
all set args->agno appropriately.

All the allocation functions that iterate AGs use it to calculate
the scan start AG. args->agno is not set until the iterator starts
walking AGs.

Hence we can easily set up a conditional check against the minimum
AG allowed in xfs_alloc_vextent_check_args() based on whether
args->agno contains NULLAGNUMBER or not and move all the repeated
setup code to xfs_alloc_vextent_check_args(), further simplifying
the allocation functions.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 50eb448..94cea96 100644 (file)
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -3089,14 +3089,18 @@ xfs_alloc_read_agf(
 static int
 xfs_alloc_vextent_check_args(
        struct xfs_alloc_arg    *args,
-       xfs_fsblock_t           target)
+       xfs_fsblock_t           target,
+       xfs_agnumber_t          *minimum_agno)
 {
        struct xfs_mount        *mp = args->mp;
        xfs_agblock_t           agsize;
 
-       args->agbno = NULLAGBLOCK;
        args->fsbno = NULLFSBLOCK;
 
+       *minimum_agno = 0;
+       if (args->tp->t_highest_agno != NULLAGNUMBER)
+               *minimum_agno = args->tp->t_highest_agno;
+
        /*
         * Just fix this up, for the case where the last a.g. is shorter
         * (or there's only one a.g.) and the caller couldn't easily figure
@@ -3123,11 +3127,16 @@ xfs_alloc_vextent_check_args(
            XFS_FSB_TO_AGBNO(mp, target) >= agsize ||
            args->minlen > args->maxlen || args->minlen > agsize ||
            args->mod >= args->prod) {
-               args->fsbno = NULLFSBLOCK;
                trace_xfs_alloc_vextent_badargs(args);
                return -ENOSPC;
        }
+
+       if (args->agno != NULLAGNUMBER && *minimum_agno > args->agno) {
+               trace_xfs_alloc_vextent_skip_deadlock(args);
+               return -ENOSPC;
+       }
        return 0;
+
 }
 
 /*
@@ -3266,28 +3275,19 @@ xfs_alloc_vextent_this_ag(
        xfs_agnumber_t          agno)
 {
        struct xfs_mount        *mp = args->mp;
-       xfs_agnumber_t          minimum_agno = 0;
+       xfs_agnumber_t          minimum_agno;
        int                     error;
 
-       if (args->tp->t_highest_agno != NULLAGNUMBER)
-               minimum_agno = args->tp->t_highest_agno;
-
-       if (minimum_agno > agno) {
-               trace_xfs_alloc_vextent_skip_deadlock(args);
-               args->fsbno = NULLFSBLOCK;
-               return 0;
-       }
-
-       error = xfs_alloc_vextent_check_args(args, XFS_AGB_TO_FSB(mp, agno, 0));
+       args->agno = agno;
+       args->agbno = 0;
+       error = xfs_alloc_vextent_check_args(args, XFS_AGB_TO_FSB(mp, agno, 0),
+                       &minimum_agno);
        if (error) {
                if (error == -ENOSPC)
                        return 0;
                return error;
        }
 
-       args->agno = agno;
-       args->agbno = 0;
-
        error = xfs_alloc_vextent_prepare_ag(args);
        if (!error && args->agbp)
                error = xfs_alloc_ag_vextent_size(args);
@@ -3400,16 +3400,15 @@ xfs_alloc_vextent_start_ag(
        xfs_fsblock_t           target)
 {
        struct xfs_mount        *mp = args->mp;
-       xfs_agnumber_t          minimum_agno = 0;
+       xfs_agnumber_t          minimum_agno;
        xfs_agnumber_t          start_agno;
        xfs_agnumber_t          rotorstep = xfs_rotorstep;
        bool                    bump_rotor = false;
        int                     error;
 
-       if (args->tp->t_highest_agno != NULLAGNUMBER)
-               minimum_agno = args->tp->t_highest_agno;
-
-       error = xfs_alloc_vextent_check_args(args, target);
+       args->agno = NULLAGNUMBER;
+       args->agbno = NULLAGBLOCK;
+       error = xfs_alloc_vextent_check_args(args, target, &minimum_agno);
        if (error) {
                if (error == -ENOSPC)
                        return 0;
@@ -3451,14 +3450,13 @@ xfs_alloc_vextent_first_ag(
        xfs_fsblock_t           target)
  {
        struct xfs_mount        *mp = args->mp;
-       xfs_agnumber_t          minimum_agno = 0;
+       xfs_agnumber_t          minimum_agno;
        xfs_agnumber_t          start_agno;
        int                     error;
 
-       if (args->tp->t_highest_agno != NULLAGNUMBER)
-               minimum_agno = args->tp->t_highest_agno;
-
-       error = xfs_alloc_vextent_check_args(args, target);
+       args->agno = NULLAGNUMBER;
+       args->agbno = NULLAGBLOCK;
+       error = xfs_alloc_vextent_check_args(args, target, &minimum_agno);
        if (error) {
                if (error == -ENOSPC)
                        return 0;
@@ -3481,28 +3479,18 @@ xfs_alloc_vextent_exact_bno(
        xfs_fsblock_t           target)
 {
        struct xfs_mount        *mp = args->mp;
-       xfs_agnumber_t          minimum_agno = 0;
+       xfs_agnumber_t          minimum_agno;
        int                     error;
 
-       if (args->tp->t_highest_agno != NULLAGNUMBER)
-               minimum_agno = args->tp->t_highest_agno;
-
-       error = xfs_alloc_vextent_check_args(args, target);
+       args->agno = XFS_FSB_TO_AGNO(mp, target);
+       args->agbno = XFS_FSB_TO_AGBNO(mp, target);
+       error = xfs_alloc_vextent_check_args(args, target, &minimum_agno);
        if (error) {
                if (error == -ENOSPC)
                        return 0;
                return error;
        }
 
-       args->agno = XFS_FSB_TO_AGNO(mp, target);
-       if (minimum_agno > args->agno) {
-               trace_xfs_alloc_vextent_skip_deadlock(args);
-               args->fsbno = NULLFSBLOCK;
-               return 0;
-       }
-
-       args->agbno = XFS_FSB_TO_AGBNO(mp, target);
-
        error = xfs_alloc_vextent_prepare_ag(args);
        if (!error && args->agbp)
                error = xfs_alloc_ag_vextent_exact(args);
@@ -3522,32 +3510,22 @@ xfs_alloc_vextent_near_bno(
        xfs_fsblock_t           target)
 {
        struct xfs_mount        *mp = args->mp;
-       xfs_agnumber_t          minimum_agno = 0;
+       xfs_agnumber_t          minimum_agno;
        bool                    needs_perag = args->pag == NULL;
        int                     error;
 
-       if (args->tp->t_highest_agno != NULLAGNUMBER)
-               minimum_agno = args->tp->t_highest_agno;
-
-       error = xfs_alloc_vextent_check_args(args, target);
+       args->agno = XFS_FSB_TO_AGNO(mp, target);
+       args->agbno = XFS_FSB_TO_AGBNO(mp, target);
+       error = xfs_alloc_vextent_check_args(args, target, &minimum_agno);
        if (error) {
                if (error == -ENOSPC)
                        return 0;
                return error;
        }
 
-       args->agno = XFS_FSB_TO_AGNO(mp, target);
-       if (minimum_agno > args->agno) {
-               trace_xfs_alloc_vextent_skip_deadlock(args);
-               args->fsbno = NULLFSBLOCK;
-               return 0;
-       }
-
        if (needs_perag)
                args->pag = xfs_perag_get(mp, args->agno);
 
-       args->agbno = XFS_FSB_TO_AGBNO(mp, target);
-
        error = xfs_alloc_vextent_prepare_ag(args);
        if (!error && args->agbp)
                error = xfs_alloc_ag_vextent_near(args);