volumefile modification awareness to make sure there are no inconsistencies.

Complete (including feature to properly umount) in my sense.

Signed-off-by: Anand V. Avati <avati@amp.gluster.com>

3 files changed, 56 insertions, 0 deletions

diff --git a/libglusterfs/src/common-utils.c b/libglusterfs/src/common-utils.c
index 1b4106c4123..e8a7c9ab525 100644
--- a/libglusterfs/src/common-utils.c
+++ b/libglusterfs/src/common-utils.c
@@ -1388,3 +1388,54 @@ gf_unlockfd (int fd)
 	return fcntl (fd, F_SETLK, &fl);
 }
   
+static void
+compute_checksum (char *buf, size_t size, uint32_t *checksum)
+{
+        int  ret = -1;
+        char *checksum_buf = NULL;
+
+        checksum_buf = (char *)(checksum);
+
+        if (!(*checksum)) {
+                checksum_buf [0] = 0xba;
+                checksum_buf [1] = 0xbe;
+                checksum_buf [2] = 0xb0;
+                checksum_buf [3] = 0x0b;                
+        }
+
+        for (ret = 0; ret < (size - 4); ret += 4) {
+                checksum_buf[0] ^= (buf[ret]);
+                checksum_buf[1] ^= (buf[ret + 1] << 1) ;
+                checksum_buf[2] ^= (buf[ret + 2] << 2);
+                checksum_buf[3] ^= (buf[ret + 3] << 3);
+        }
+
+        for (ret = 0; ret <= (size % 4); ret++) {
+                checksum_buf[ret] ^= (buf[(size - 4) + ret] << ret);
+        }
+        
+        return;
+}
+
+#define GF_CHECKSUM_BUF_SIZE 1024
+
+int
+get_checksum_for_file (int fd, uint32_t *checksum) 
+{
+        int ret = -1;
+        char buf[GF_CHECKSUM_BUF_SIZE] = {0,};
+
+        /* goto first place */
+        lseek (fd, 0L, SEEK_SET);
+        do {
+                ret = read (fd, &buf, GF_CHECKSUM_BUF_SIZE);
+                if (ret > 0)
+                        compute_checksum (buf, GF_CHECKSUM_BUF_SIZE, 
+                                          checksum);
+        } while (ret > 0);
+
+        /* set it back */
+        lseek (fd, 0L, SEEK_SET);
+
+        return ret;
+}
diff --git a/libglusterfs/src/common-utils.h b/libglusterfs/src/common-utils.h
index f3a39226c03..b3630d478a7 100644
--- a/libglusterfs/src/common-utils.h
+++ b/libglusterfs/src/common-utils.h
@@ -310,5 +310,7 @@ int gf_string2time (const char *str, uint32_t *n);
 int gf_lockfd (int fd);
 int gf_unlockfd (int fd);
 
+int get_checksum_for_file (int fd, uint32_t *checksum);
+
 #endif /* _COMMON_UTILS_H */
 
diff --git a/libglusterfs/src/glusterfs.h b/libglusterfs/src/glusterfs.h
index be6412f224d..d00ec48668c 100644
--- a/libglusterfs/src/glusterfs.h
+++ b/libglusterfs/src/glusterfs.h
@@ -227,6 +227,7 @@ struct _cmd_args {
 
 	/* fuse options */
 	int              fuse_direct_io_mode_flag;
+        int              volfile_check;
 	double           fuse_entry_timeout;
 	double           fuse_attribute_timeout;
 	char            *volume_name;
@@ -258,6 +259,7 @@ struct _glusterfs_ctx {
 	void              *event_pool;
 	pthread_mutex_t    lock;
 	int                xl_count;
+        uint32_t           volfile_checksum;
 };
 
 typedef struct _glusterfs_ctx glusterfs_ctx_t;
@@ -272,6 +274,7 @@ typedef enum {
   GF_EVENT_CHILD_CONNECTING,
   GF_EVENT_TRANSPORT_CLEANUP,
   GF_EVENT_TRANSPORT_CONNECTED,
+  GF_EVENT_VOLFILE_MODIFIED,
 } glusterfs_event_t;
 
 #define GF_MUST_CHECK __attribute__((warn_unused_result))