From 1e7118e498bb178971478d5c1fb06c86c2098312 Mon Sep 17 00:00:00 2001 From: Miles Bader Date: Sun, 9 Jul 1995 16:01:00 +0000 Subject: (diskfs_pager_users): New function. --- ext2fs/pager.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) diff --git a/ext2fs/pager.c b/ext2fs/pager.c index ba69f00f..97fdd31b 100644 --- a/ext2fs/pager.c +++ b/ext2fs/pager.c @@ -774,3 +774,71 @@ diskfs_sync_everything (int wait) /* Do things on the the disk pager. */ pokel_sync (&global_pokel, wait); } + +/* ---------------------------------------------------------------- */ + +/* Tell diskfs if there are pagers exported, and if none, then + prevent any new ones from showing up. */ +int +diskfs_pager_users () +{ + int npagers; + + error_t block_cache (void *arg) + { + struct pager *p = arg; + + pager_change_attributes (p, 0, MEMORY_OBJECT_COPY_DELAY, 1); + return 0; + } + + error_t enable_cache (void *arg) + { + struct pager *p = arg; + struct user_pager_info *upi = pager_get_upi (p); + + pager_change_attributes (p, 1, MEMORY_OBJECT_COPY_DELAY, 0); + + /* It's possible that we didn't have caching on before, because + the user here is the only reference to the underlying node + (actually, that's quite likely inside this particular + routine), and if that node has no links. So dinkle the node + ref counting scheme here, which will cause caching to be + turned off, if that's really necessary. */ + if (upi->type == FILE_DATA) + { + diskfs_nref (upi->node); + diskfs_nrele (upi->node); + } + + return 0; + } + + npagers = ports_count_bucket (pager_bucket); + if (npagers == 0) + return 0; + + if (MAY_CACHE == 0) + { + ports_enable_bucket (pager_bucket); + return 1; + } + + /* Loop through the pagers and turn off caching one by one, + synchronously. That should cause termination of each pager. */ + ports_bucket_iterate (pager_bucket, block_cache); + + /* Give it a second; the kernel doesn't actually shutdown + immediately. XXX */ + sleep (1); + + npagers = ports_count_bucket (pager_bucket); + + if (npagers == 0) + return 0; + + /* Darn, there are actual honest users. Turn caching back on, + and return failure. */ + ports_bucket_iterate (pager_bucket, enable_cache); + return 1; +} -- cgit v1.2.3