JFFS2: Optimize building lists during scan
authorMark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
Wed, 1 Jul 2015 04:38:26 +0000 (16:38 +1200)
committerLothar Waßmann <LW@KARO-electronics.de>
Thu, 10 Sep 2015 06:24:12 +0000 (08:24 +0200)
If the flash is slow, reading less from the flash into buffers makes
the process faster.

Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
fs/jffs2/jffs2_1pass.c

index e58e7d2..f488537 100644 (file)
@@ -1501,7 +1501,7 @@ jffs2_1pass_build_lists(struct part_info * part)
        u32 counterF = 0;
        u32 counterN = 0;
        u32 max_totlen = 0;
-       u32 buf_size = DEFAULT_EMPTY_SCAN_SIZE;
+       u32 buf_size;
        char *buf;
 
        nr_sectors = lldiv(part->size, part->sector_size);
@@ -1513,7 +1513,7 @@ jffs2_1pass_build_lists(struct part_info * part)
        /* if we are building a list we need to refresh the cache. */
        jffs_init_1pass_list(part);
        pL = (struct b_lists *)part->jffs2_priv;
-       buf = malloc(buf_size);
+       buf = malloc(DEFAULT_EMPTY_SCAN_SIZE);
        puts ("Scanning JFFS2 FS:   ");
 
        /* start at the beginning of the partition */
@@ -1529,6 +1529,8 @@ jffs2_1pass_build_lists(struct part_info * part)
                int ret;
 #endif
 
+               /* Set buf_size to maximum length */
+               buf_size = DEFAULT_EMPTY_SCAN_SIZE;
                WATCHDOG_RESET();
 
 #ifdef CONFIG_JFFS2_SUMMARY
@@ -1603,6 +1605,11 @@ jffs2_1pass_build_lists(struct part_info * part)
 
                ofs += sector_ofs;
                prevofs = ofs - 1;
+               /*
+                * Set buf_size down to the minimum size required.
+                * This prevents reading in chunks of flash data unnecessarily.
+                */
+               buf_size = sizeof(union jffs2_node_union);
 
        scan_more:
                while (ofs < sector_ofs + part->sector_size) {
@@ -1683,13 +1690,18 @@ jffs2_1pass_build_lists(struct part_info * part)
                        case JFFS2_NODETYPE_INODE:
                                if (buf_ofs + buf_len < ofs + sizeof(struct
                                                        jffs2_raw_inode)) {
+                                       buf_len = min_t(uint32_t,
+                                                       sizeof(struct jffs2_raw_inode),
+                                                       sector_ofs +
+                                                       part->sector_size -
+                                                       ofs);
                                        get_fl_mem((u32)part->offset + ofs,
                                                   buf_len, buf);
                                        buf_ofs = ofs;
                                        node = (void *)buf;
                                }
-                               if (!inode_crc((struct jffs2_raw_inode *) node))
-                                      break;
+                               if (!inode_crc((struct jffs2_raw_inode *)node))
+                                       break;
 
                                if (insert_node(&pL->frag, (u32) part->offset +
                                                ofs) == NULL) {
@@ -1706,6 +1718,11 @@ jffs2_1pass_build_lists(struct part_info * part)
                                                        ((struct
                                                         jffs2_raw_dirent *)
                                                        node)->nsize) {
+                                       buf_len = min_t(uint32_t,
+                                                       node->totlen,
+                                                       sector_ofs +
+                                                       part->sector_size -
+                                                       ofs);
                                        get_fl_mem((u32)part->offset + ofs,
                                                   buf_len, buf);
                                        buf_ofs = ofs;