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Date: Thu, 20 Jun 2013 01:14:01 +0800
From: Eryu Guan <guaneryu@...il.com>
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu, Eryu Guan <guaneryu@...il.com>
Subject: [PATCH 2/2] blkid: fix broken garbage collection
'blkid -g' fails to perform garbage collection on the blkid cache
since commit
fe144e1 libblkid: Refuse to create a device structure for a non-existent device
Non-existent devices won't be added to the cache->bic_devs list, so
blkid_gc_cache() couldn't even know the to-be-gc'ed devices.
To fix that a new cache flag BLKID_BIC_FL_GC is added to indicate that
there are stale devices in cache to be gc'ed, as devices are all valid
in cache->bic_devs we can just write out the cache to disk to perform
the garbage collection.
Tested by adding non-existent device entry to blkid.tab and running
'blkid -g' to see whether the entry is removed. 'make -C lib/blkid
check' reported no failures too.
Also fix the return value of 'blkid -g', return 0 instead.
Signed-off-by: Eryu Guan <guaneryu@...il.com>
---
lib/blkid/blkidP.h | 1 +
lib/blkid/cache.c | 25 +++++++------------------
lib/blkid/devname.c | 4 +++-
misc/blkid.c | 1 +
4 files changed, 12 insertions(+), 19 deletions(-)
diff --git a/lib/blkid/blkidP.h b/lib/blkid/blkidP.h
index a99b242..f236400 100644
--- a/lib/blkid/blkidP.h
+++ b/lib/blkid/blkidP.h
@@ -100,6 +100,7 @@ struct blkid_struct_cache
#define BLKID_BIC_FL_PROBED 0x0002 /* We probed /proc/partition devices */
#define BLKID_BIC_FL_CHANGED 0x0004 /* Cache has changed from disk */
+#define BLKID_BIC_FL_GC 0x0008 /* Cache has stale devices */
extern char *blkid_strdup(const char *s);
extern char *blkid_strndup(const char *s, const int length);
diff --git a/lib/blkid/cache.c b/lib/blkid/cache.c
index 1b6a86d..0a68639 100644
--- a/lib/blkid/cache.c
+++ b/lib/blkid/cache.c
@@ -159,26 +159,15 @@ void blkid_put_cache(blkid_cache cache)
void blkid_gc_cache(blkid_cache cache)
{
- struct list_head *p, *pnext;
- struct stat st;
-
- if (!cache)
+ if (!cache || !(cache->bic_flags & BLKID_BIC_FL_GC))
return;
- list_for_each_safe(p, pnext, &cache->bic_devs) {
- blkid_dev dev = list_entry(p, struct blkid_struct_dev, bid_devs);
- if (!p)
- break;
- if (stat(dev->bid_name, &st) < 0) {
- DBG(DEBUG_CACHE,
- printf("freeing %s\n", dev->bid_name));
- blkid_free_dev(dev);
- cache->bic_flags |= BLKID_BIC_FL_CHANGED;
- } else {
- DBG(DEBUG_CACHE,
- printf("Device %s exists\n", dev->bid_name));
- }
- }
+ /*
+ * Only valid devices are kept in cache, set BLKID_BIC_FL_CHANGED
+ * to write cache to disk to perform a garbage collection.
+ */
+ cache->bic_flags |= BLKID_BIC_FL_CHANGED;
+ return;
}
diff --git a/lib/blkid/devname.c b/lib/blkid/devname.c
index a6673c1..0d8e66f 100644
--- a/lib/blkid/devname.c
+++ b/lib/blkid/devname.c
@@ -66,8 +66,10 @@ blkid_dev blkid_get_dev(blkid_cache cache, const char *devname, int flags)
}
if (!dev && (flags & BLKID_DEV_CREATE)) {
- if (access(devname, F_OK) < 0)
+ if (access(devname, F_OK) < 0) {
+ cache->bic_flags |= BLKID_BIC_FL_GC;
return NULL;
+ }
dev = blkid_new_dev();
if (!dev)
return NULL;
diff --git a/misc/blkid.c b/misc/blkid.c
index a4a8db0..b269eeb 100644
--- a/misc/blkid.c
+++ b/misc/blkid.c
@@ -365,6 +365,7 @@ int main(int argc, char **argv)
err = 2;
if (gc) {
blkid_gc_cache(cache);
+ err = 0;
goto exit;
}
if (output_format & OUTPUT_PRETTY_LIST)
--
1.8.2.1
--
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