scrub/descr.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2019 Oracle.  All Rights Reserved.
   4  * Author: Darrick J. Wong <darrick.wong@oracle.com>
   5  */
   6 #include "xfs.h"
   7 #include <assert.h>
   8 #include <sys/statvfs.h>
   9 #include "platform_defs.h"
  10 #include "input.h"
  11 #include "libfrog/paths.h"
  12 #include "libfrog/ptvar.h"
  13 #include "xfs_scrub.h"
  14 #include "common.h"
  15 #include "descr.h"
  16
  17 /*
  18  * Deferred String Description Renderer
  19  * ====================================
  20  * There are many places in xfs_scrub where some event occurred and we'd like
  21  * to be able to print some sort of message describing what happened, and
  22  * where.  However, we don't know whether we're going to need the description
  23  * of where ahead of time and there's little point in spending any time looking
  24  * up gettext strings and formatting buffers until we actually need to.
  25  *
  26  * This code provides enough of a function closure that we are able to record
  27  * some information about the program status but defer rendering the textual
  28  * description until we know that we need it.  Once we've rendered the string
  29  * we can skip it for subsequent calls.  We use per-thread storage for the
  30  * message buffer to amortize the memory allocation across calls.
  31  *
  32  * On a clean filesystem this can reduce the xfs_scrub runtime by 7-10% by
  33  * avoiding unnecessary work.
  34  */
  35
  36 static struct ptvar *descr_ptvar;
  37
  38 /* Global buffer for when we aren't running in threaded mode. */
  39 static char global_dsc_buf[DESCR_BUFSZ];
  40
  41 /*
  42  * Render a textual description string using the function and location stored
  43  * in the description context.
  44  */
  45 const char *
  46 __descr_render(
  47         struct descr            *dsc,
  48         const char              *file,
  49         int                     line)
  50 {
  51         char                    *dsc_buf;
  52         int                     ret;
  53
  54         if (descr_ptvar) {
  55                 dsc_buf = ptvar_get(descr_ptvar, &ret);
  56                 if (ret)
  57                         return _("error finding description buffer");
  58         } else
  59                 dsc_buf = global_dsc_buf;
  60
  61         ret = dsc->fn(dsc->ctx, dsc_buf, DESCR_BUFSZ, dsc->where);
  62         if (ret < 0) {
  63                 snprintf(dsc_buf, DESCR_BUFSZ,
  64 _("error %d while rendering description at %s line %d\n"),
  65                                 ret, file, line);
  66         }
  67
  68         return dsc_buf;
  69 }
  70
  71 /*
  72  * Set a new location context for this deferred-rendering string.
  73  * The caller is responsible for freeing the old context, if any.
  74  */
  75 void
  76 descr_set(
  77         struct descr            *dsc,
  78         void                    *where)
  79 {
  80         dsc->where = where;
  81 }
  82
  83 /* Allocate all the description string buffers. */
  84 int
  85 descr_init_phase(
  86         struct scrub_ctx        *ctx,
  87         unsigned int            nr_threads)
  88 {
  89         int                     ret;
  90
  91         assert(descr_ptvar == NULL);
  92         ret = ptvar_alloc(nr_threads, DESCR_BUFSZ, &descr_ptvar);
  93         if (ret)
  94                 str_liberror(ctx, ret, _("creating description buffer"));
  95
  96         return ret;
  97 }
  98
  99 /* Free all the description string buffers. */
 100 void
 101 descr_end_phase(void)
 102 {
 103         if (descr_ptvar)
 104                 ptvar_free(descr_ptvar);
 105         descr_ptvar = NULL;
 106 }