[Sheepdog] [PATCH v6 08/17] farm: remove stale object in backend store
Liu Yuan
namei.unix at gmail.com
Thu Jan 12 14:37:19 CET 2012
From: Liu Yuan <tailai.ly at taobao.com>
For storing one object into backend store, either
a) no content change, then point to the same old sha1_file (no stale object)
or
b) content updated, then will point to a new object with a new sha1.
So we need to remove stale object in case b), only in the assumption it is the
object generated by recovery code. [*]
When we try store new snapshot object into the backend store, it is safe and
good timing for us to remove the old object with the same object ID.
[*] Here I assume we don't need to restore to 'sys epoch' state.
Signed-off-by: Liu Yuan <tailai.ly at taobao.com>
---
sheep/farm/farm.h | 2 +
sheep/farm/trunk.c | 149 +++++++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 149 insertions(+), 2 deletions(-)
diff --git a/sheep/farm/farm.h b/sheep/farm/farm.h
index 5734903..bf8654c 100644
--- a/sheep/farm/farm.h
+++ b/sheep/farm/farm.h
@@ -62,5 +62,7 @@ extern int trunk_file_write(unsigned char *outsha1, int user);
extern void *trunk_file_read(unsigned char *sha1, struct sha1_file_hdr *);
extern int trunk_update_entry(uint64_t oid);
extern void trunk_reset(void);
+extern void trunk_put_entry(uint64_t oid);
+extern void trunk_get_entry(uint64_t oid);
#endif
diff --git a/sheep/farm/trunk.c b/sheep/farm/trunk.c
index 0506f3f..d10da85 100644
--- a/sheep/farm/trunk.c
+++ b/sheep/farm/trunk.c
@@ -18,6 +18,8 @@
*/
#include <pthread.h>
#include <dirent.h>
+#include <sys/stat.h>
+#include <unistd.h>
#include "farm.h"
#include "strbuf.h"
@@ -36,6 +38,11 @@ static struct hlist_head trunk_hashtable[HASH_SIZE];
static pthread_mutex_t hashtable_lock[HASH_SIZE] = { [0 ... HASH_SIZE - 1] = PTHREAD_MUTEX_INITIALIZER };
static unsigned int trunk_entry_active_nr;
+struct omap_entry {
+ uint64_t oid;
+ unsigned char sha1[SHA1_LEN];
+};
+
static inline int trunk_entry_is_dirty(struct trunk_entry_incore *entry)
{
return entry->flags & TRUNK_ENTRY_DIRTY;
@@ -91,6 +98,27 @@ out:
return entry;
}
+static int create_files(void)
+{
+ int fd, ret = 0;
+ struct strbuf buf = STRBUF_INIT;
+
+ strbuf_addstr(&buf, farm_dir);
+ strbuf_addf(&buf, "/%s", "sys_omap");
+
+ fd = open(buf.buf, O_CREAT | O_EXCL, 0666);
+ if (fd < 0) {
+ if (errno != EEXIST) {
+ ret = -1;
+ goto out;
+ }
+ }
+ close(fd);
+out:
+ strbuf_release(&buf);
+ return ret;
+}
+
int trunk_init(void)
{
DIR *dir;
@@ -109,6 +137,10 @@ int trunk_init(void)
continue;
lookup_trunk_entry(oid, 1);
}
+
+ if (create_files() < 0)
+ return -1;
+
closedir(dir);
return 0;
}
@@ -142,7 +174,8 @@ static int fill_entry_new_sha1(struct trunk_entry_incore *entry)
close(fd);
goto out;
}
- dprintf("oid: %"PRIx64"\n", entry->raw.oid);
+ dprintf("data sha1:%s, %"PRIx64"\n", sha1_to_hex(entry->raw.sha1),
+ entry->raw.oid);
out:
strbuf_release(&buf);
return ret;
@@ -163,9 +196,91 @@ static void inline put_entry(struct trunk_entry_incore *entry)
free(entry);
}
+static int omap_file_init(struct strbuf *outbuf)
+{
+ int fd;
+ int len = -1;
+ void *buffer = NULL;
+ struct strbuf buf = STRBUF_INIT;
+ struct stat st;
+
+ strbuf_addf(&buf, "%s/%s", farm_dir, "sys_omap");
+ fd = open(buf.buf, O_RDONLY);
+ if (fd < 0)
+ goto out;
+
+ if (fstat(fd, &st) < 0) {
+ dprintf("%m\n");
+ goto out_close;
+ }
+
+ len = st.st_size;
+ if (len == 0)
+ goto out_close;
+
+ buffer = xmalloc(len);
+ len = xread(fd, buffer, len);
+ if (len != st.st_size) {
+ len = -1;
+ goto out_close;
+ }
+ strbuf_add(outbuf, buffer, len);
+out_close:
+ close(fd);
+out:
+ strbuf_release(&buf);
+ free(buffer);
+ return len;
+}
+
+static int omap_file_final(struct strbuf *omap_buf)
+{
+ int fd, ret = -1;
+ struct strbuf buf = STRBUF_INIT;
+
+ if (omap_buf->len == 0)
+ return 0;
+
+ strbuf_addf(&buf, "%s/%s", farm_dir, "sys_omap");
+ fd = open(buf.buf, O_WRONLY | O_TRUNC);
+ if (fd < 0) {
+ dprintf("%m\n");
+ goto out;
+ }
+
+ ret = xwrite(fd, omap_buf->buf, omap_buf->len);
+ if (ret != omap_buf->len)
+ ret = -1;
+
+ close(fd);
+out:
+ strbuf_release(&buf);
+ return ret;
+}
+
+static struct omap_entry *omap_file_insert(struct strbuf *buf, struct omap_entry *new)
+{
+ unsigned i, nr = buf->len / sizeof(struct omap_entry);
+ struct omap_entry *omap_buf = (struct omap_entry *)buf->buf;
+ for (i = 0; i < nr; i++, omap_buf++)
+ if (omap_buf->oid == new->oid) {
+ if (memcmp(omap_buf->sha1, new->sha1, SHA1_LEN) == 0)
+ return NULL;
+ else {
+ struct omap_entry *old = xmalloc(sizeof(*old));
+ memcpy(old, omap_buf, sizeof(*old));
+ memcpy(omap_buf->sha1, new->sha1, SHA1_LEN);
+ return old;
+ }
+ }
+ dprintf("oid, %"PRIx64"\n", new->oid);
+ strbuf_add(buf, new, sizeof(*new));
+ return NULL;
+}
+
int trunk_file_write(unsigned char *outsha1, int user)
{
- struct strbuf buf;
+ struct strbuf buf, omap_buf = STRBUF_INIT;
uint64_t data_size = sizeof(struct trunk_entry) * trunk_entry_active_nr;
struct sha1_file_hdr hdr = { .size = data_size,
.priv = trunk_entry_active_nr };
@@ -174,6 +289,7 @@ int trunk_file_write(unsigned char *outsha1, int user)
memcpy(hdr.tag, TAG_TRUNK, TAG_LEN);
strbuf_init(&buf, sizeof(hdr) + data_size);
+ omap_file_init(&omap_buf);
strbuf_add(&buf, &hdr, sizeof(hdr));
list_for_each_entry_safe(entry, t, &trunk_active_list, active_list) {
@@ -184,8 +300,21 @@ int trunk_file_write(unsigned char *outsha1, int user)
}
}
strbuf_add(&buf, &entry->raw, sizeof(struct trunk_entry));
+ if (!user) {
+ struct omap_entry new = { .oid = entry->raw.oid }, *old;
+ memcpy(new.sha1, entry->raw.sha1, SHA1_LEN);
+ old = omap_file_insert(&omap_buf, &new);
+ if (old) {
+ dprintf("try delete stale snapshot object %"PRIx64"\n", old->oid);
+ sha1_file_try_delete(old->sha1);
+ free(old);
+ }
+ }
undirty_trunk_entry(entry);
}
+ if (omap_file_final(&omap_buf) < 0)
+ eprintf("omap_file_final failed\n");
+
if (sha1_file_write((void *)buf.buf, buf.len, outsha1) < 0) {
ret = -1;
goto out;
@@ -193,6 +322,7 @@ int trunk_file_write(unsigned char *outsha1, int user)
dprintf("trunk sha1: %s\n", sha1_to_hex(outsha1));
out:
strbuf_release(&buf);
+ strbuf_release(&omap_buf);
return ret;
}
@@ -223,6 +353,21 @@ int trunk_update_entry(uint64_t oid)
return 0;
}
+void trunk_put_entry(uint64_t oid)
+{
+ struct trunk_entry_incore *entry;
+
+ entry = lookup_trunk_entry(oid, 0);
+ if (entry)
+ /* When it is supposed to be put, no IO requests for it */
+ put_entry(entry);
+}
+
+void trunk_get_entry(uint64_t oid)
+{
+ lookup_trunk_entry(oid, 1);
+}
+
void trunk_reset(void)
{
struct trunk_entry_incore *entry, *t;
--
1.7.8.2
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