jffs2: Improve post-mount CRC scan efficiency
We need to finish doing the CRC checks before we can allow writes to
happen, and we currently process the inodes in order. This means a call
to jffs2_get_ino_cache() for each possible inode# up to c->highest_ino.
There may be a lot of lookups which fail, if the inode# space is used
sparsely. And the inode# space is *often* used sparsely, if a file
system contains a lot of stuff that was put there in the original
image, followed by lots of creation and deletion of new files.
Instead of processing them numerically with a lookup each time, just
walk the hash buckets instead.
[fix locking typo reported by Dan Carpenter]
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/fs/jffs2/gc.c b/fs/jffs2/gc.c
index 5a2dec2..61c5547 100644
--- a/fs/jffs2/gc.c
+++ b/fs/jffs2/gc.c
@@ -134,38 +134,60 @@
if (mutex_lock_interruptible(&c->alloc_sem))
return -EINTR;
+
for (;;) {
+ /* We can't start doing GC until we've finished checking
+ the node CRCs etc. */
+ int bucket, want_ino;
+
spin_lock(&c->erase_completion_lock);
if (!c->unchecked_size)
break;
-
- /* We can't start doing GC yet. We haven't finished checking
- the node CRCs etc. Do it now. */
-
- /* checked_ino is protected by the alloc_sem */
- if (c->checked_ino > c->highest_ino && xattr) {
- pr_crit("Checked all inodes but still 0x%x bytes of unchecked space?\n",
- c->unchecked_size);
- jffs2_dbg_dump_block_lists_nolock(c);
- spin_unlock(&c->erase_completion_lock);
- mutex_unlock(&c->alloc_sem);
- return -ENOSPC;
- }
-
spin_unlock(&c->erase_completion_lock);
if (!xattr)
xattr = jffs2_verify_xattr(c);
spin_lock(&c->inocache_lock);
+ /* Instead of doing the inodes in numeric order, doing a lookup
+ * in the hash for each possible number, just walk the hash
+ * buckets of *existing* inodes. This means that we process
+ * them out-of-order, but it can be a lot faster if there's
+ * a sparse inode# space. Which there often is. */
+ want_ino = c->check_ino;
+ for (bucket = c->check_ino % c->inocache_hashsize ; bucket < c->inocache_hashsize; bucket++) {
+ for (ic = c->inocache_list[bucket]; ic; ic = ic->next) {
+ if (ic->ino < want_ino)
+ continue;
- ic = jffs2_get_ino_cache(c, c->checked_ino++);
+ if (ic->state != INO_STATE_CHECKEDABSENT &&
+ ic->state != INO_STATE_PRESENT)
+ goto got_next; /* with inocache_lock held */
- if (!ic) {
- spin_unlock(&c->inocache_lock);
- continue;
+ jffs2_dbg(1, "Skipping ino #%u already checked\n",
+ ic->ino);
+ }
+ want_ino = 0;
}
+ /* Point c->check_ino past the end of the last bucket. */
+ c->check_ino = ((c->highest_ino + c->inocache_hashsize + 1) &
+ ~c->inocache_hashsize) - 1;
+
+ spin_unlock(&c->inocache_lock);
+
+ pr_crit("Checked all inodes but still 0x%x bytes of unchecked space?\n",
+ c->unchecked_size);
+ jffs2_dbg_dump_block_lists_nolock(c);
+ mutex_unlock(&c->alloc_sem);
+ return -ENOSPC;
+
+ got_next:
+ /* For next time round the loop, we want c->checked_ino to indicate
+ * the *next* one we want to check. And since we're walking the
+ * buckets rather than doing it sequentially, it's: */
+ c->check_ino = ic->ino + c->inocache_hashsize;
+
if (!ic->pino_nlink) {
jffs2_dbg(1, "Skipping check of ino #%d with nlink/pino zero\n",
ic->ino);
@@ -176,8 +198,6 @@
switch(ic->state) {
case INO_STATE_CHECKEDABSENT:
case INO_STATE_PRESENT:
- jffs2_dbg(1, "Skipping ino #%u already checked\n",
- ic->ino);
spin_unlock(&c->inocache_lock);
continue;
@@ -196,7 +216,7 @@
ic->ino);
/* We need to come back again for the _same_ inode. We've
made no progress in this case, but that should be OK */
- c->checked_ino--;
+ c->check_ino = ic->ino;
mutex_unlock(&c->alloc_sem);
sleep_on_spinunlock(&c->inocache_wq, &c->inocache_lock);