[PATCH] Manage jbd allocations from its own slabs
JBD currently allocates commit and frozen buffers from slabs. With
CONFIG_SLAB_DEBUG, its possible for an allocation to cross the page
boundary causing IO problems.
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=200127
So, instead of allocating these from regular slabs - manage allocation from
its own slabs and disable slab debug for these slabs.
[akpm@osdl.org: cleanups]
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c
index 8c9b28d..f66724c 100644
--- a/fs/jbd/journal.c
+++ b/fs/jbd/journal.c
@@ -84,6 +84,7 @@
static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
static void __journal_abort_soft (journal_t *journal, int errno);
+static int journal_create_jbd_slab(size_t slab_size);
/*
* Helper function used to manage commit timeouts
@@ -328,10 +329,10 @@
char *tmp;
jbd_unlock_bh_state(bh_in);
- tmp = jbd_rep_kmalloc(bh_in->b_size, GFP_NOFS);
+ tmp = jbd_slab_alloc(bh_in->b_size, GFP_NOFS);
jbd_lock_bh_state(bh_in);
if (jh_in->b_frozen_data) {
- kfree(tmp);
+ jbd_slab_free(tmp, bh_in->b_size);
goto repeat;
}
@@ -1069,17 +1070,17 @@
int journal_load(journal_t *journal)
{
int err;
+ journal_superblock_t *sb;
err = load_superblock(journal);
if (err)
return err;
+ sb = journal->j_superblock;
/* If this is a V2 superblock, then we have to check the
* features flags on it. */
if (journal->j_format_version >= 2) {
- journal_superblock_t *sb = journal->j_superblock;
-
if ((sb->s_feature_ro_compat &
~cpu_to_be32(JFS_KNOWN_ROCOMPAT_FEATURES)) ||
(sb->s_feature_incompat &
@@ -1090,6 +1091,13 @@
}
}
+ /*
+ * Create a slab for this blocksize
+ */
+ err = journal_create_jbd_slab(cpu_to_be32(sb->s_blocksize));
+ if (err)
+ return err;
+
/* Let the recovery code check whether it needs to recover any
* data from the journal. */
if (journal_recover(journal))
@@ -1612,6 +1620,77 @@
}
/*
+ * jbd slab management: create 1k, 2k, 4k, 8k slabs as needed
+ * and allocate frozen and commit buffers from these slabs.
+ *
+ * Reason for doing this is to avoid, SLAB_DEBUG - since it could
+ * cause bh to cross page boundary.
+ */
+
+#define JBD_MAX_SLABS 5
+#define JBD_SLAB_INDEX(size) (size >> 11)
+
+static kmem_cache_t *jbd_slab[JBD_MAX_SLABS];
+static const char *jbd_slab_names[JBD_MAX_SLABS] = {
+ "jbd_1k", "jbd_2k", "jbd_4k", NULL, "jbd_8k"
+};
+
+static void journal_destroy_jbd_slabs(void)
+{
+ int i;
+
+ for (i = 0; i < JBD_MAX_SLABS; i++) {
+ if (jbd_slab[i])
+ kmem_cache_destroy(jbd_slab[i]);
+ jbd_slab[i] = NULL;
+ }
+}
+
+static int journal_create_jbd_slab(size_t slab_size)
+{
+ int i = JBD_SLAB_INDEX(slab_size);
+
+ BUG_ON(i >= JBD_MAX_SLABS);
+
+ /*
+ * Check if we already have a slab created for this size
+ */
+ if (jbd_slab[i])
+ return 0;
+
+ /*
+ * Create a slab and force alignment to be same as slabsize -
+ * this will make sure that allocations won't cross the page
+ * boundary.
+ */
+ jbd_slab[i] = kmem_cache_create(jbd_slab_names[i],
+ slab_size, slab_size, 0, NULL, NULL);
+ if (!jbd_slab[i]) {
+ printk(KERN_EMERG "JBD: no memory for jbd_slab cache\n");
+ return -ENOMEM;
+ }
+ return 0;
+}
+
+void * jbd_slab_alloc(size_t size, gfp_t flags)
+{
+ int idx;
+
+ idx = JBD_SLAB_INDEX(size);
+ BUG_ON(jbd_slab[idx] == NULL);
+ return kmem_cache_alloc(jbd_slab[idx], flags | __GFP_NOFAIL);
+}
+
+void jbd_slab_free(void *ptr, size_t size)
+{
+ int idx;
+
+ idx = JBD_SLAB_INDEX(size);
+ BUG_ON(jbd_slab[idx] == NULL);
+ kmem_cache_free(jbd_slab[idx], ptr);
+}
+
+/*
* Journal_head storage management
*/
static kmem_cache_t *journal_head_cache;
@@ -1799,13 +1878,13 @@
printk(KERN_WARNING "%s: freeing "
"b_frozen_data\n",
__FUNCTION__);
- kfree(jh->b_frozen_data);
+ jbd_slab_free(jh->b_frozen_data, bh->b_size);
}
if (jh->b_committed_data) {
printk(KERN_WARNING "%s: freeing "
"b_committed_data\n",
__FUNCTION__);
- kfree(jh->b_committed_data);
+ jbd_slab_free(jh->b_committed_data, bh->b_size);
}
bh->b_private = NULL;
jh->b_bh = NULL; /* debug, really */
@@ -1961,6 +2040,7 @@
journal_destroy_revoke_caches();
journal_destroy_journal_head_cache();
journal_destroy_handle_cache();
+ journal_destroy_jbd_slabs();
}
static int __init journal_init(void)