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Commit 3c0ed9c3a561ca744b2b76921bb8352ba2340669

Authored by Stefan Brüns
Committed by Tom Rini
1 parent ed76f91277
Exists in v2017.01-smarct4x and in 25 other branches 8qm-imx_v2020.04_5.4.70_2.3.0, emb_lf_v2022.04, pitx_8mp_lf_v2020.04, smarc-8m-android-10.0.0_2.6.0, smarc-8m-android-11.0.0_2.0.0, smarc-8mp-android-11.0.0_2.0.0, smarc-imx6_v2018.03_4.14.98_2.0.0_ga, smarc-imx7_v2017.03_4.9.11_1.0.0_ga, smarc-imx7_v2018.03_4.14.98_2.0.0_ga, smarc-imx_v2017.03_4.9.11_1.0.0_ga, smarc-imx_v2017.03_4.9.88_2.0.0_ga, smarc-imx_v2017.03_o8.1.0_1.3.0_8m, smarc-imx_v2018.03_4.14.78_1.0.0_ga, smarc-n7.1.2_2.0.0-ga, smarc_8m-imx_v2018.03_4.14.98_2.0.0_ga, smarc_8m-imx_v2019.04_4.19.35_1.1.0, smarc_8m_00d0-imx_v2018.03_4.14.98_2.0.0_ga, smarc_8mm-imx_v2018.03_4.14.98_2.0.0_ga, smarc_8mm-imx_v2019.04_4.19.35_1.1.0, smarc_8mm-imx_v2020.04_5.4.24_2.1.0, smarc_8mp_lf_v2020.04, smarc_8mq-imx_v2020.04_5.4.24_2.1.0, smarc_8mq_lf_v2020.04, v2017.01-smarct3x, v2017.01-smarct3x-emmc

fs/fat: Do not write unmodified fat entries to disk 

The code caches 6 sectors of the FAT. On FAT traversal, the old contents
needs to be flushed to disk, but only if any FAT entries had been modified.
Explicitly flag the buffer on modification.

Currently, creating a new file traverses the whole FAT up to the first
free cluster and rewrites the on-disk blocks.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>

Showing 3 changed files with 21 additions and 12 deletions Side-by-side Diff

... ... @@ -876,6 +876,7 @@
876 876 }
877 877  
878 878 mydata->fatbufnum = -1;
  879 + mydata->fat_dirty = 0;
879 880 mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
880 881 if (mydata->fatbuf == NULL) {
881 882 debug("Error: allocating memory\n");
... ... @@ -104,13 +104,19 @@
104 104 /*
105 105 * Write fat buffer into block device
106 106 */
107   -static int flush_fat_buffer(fsdata *mydata)
  107 +static int flush_dirty_fat_buffer(fsdata *mydata)
108 108 {
109 109 int getsize = FATBUFBLOCKS;
110 110 __u32 fatlength = mydata->fatlength;
111 111 __u8 *bufptr = mydata->fatbuf;
112 112 __u32 startblock = mydata->fatbufnum * FATBUFBLOCKS;
113 113  
  114 + debug("debug: evicting %d, dirty: %d\n", mydata->fatbufnum,
  115 + (int)mydata->fat_dirty);
  116 +
  117 + if ((!mydata->fat_dirty) || (mydata->fatbufnum == -1))
  118 + return 0;
  119 +
114 120 startblock += mydata->fat_sect;
115 121  
116 122 if (getsize > fatlength)
... ... @@ -130,6 +136,7 @@
130 136 return -1;
131 137 }
132 138 }
  139 + mydata->fat_dirty = 0;
133 140  
134 141 return 0;
135 142 }
... ... @@ -186,10 +193,8 @@
186 193 startblock += mydata->fat_sect; /* Offset from start of disk */
187 194  
188 195 /* Write back the fatbuf to the disk */
189   - if (mydata->fatbufnum != -1) {
190   - if (flush_fat_buffer(mydata) < 0)
191   - return -1;
192   - }
  196 + if (flush_dirty_fat_buffer(mydata) < 0)
  197 + return -1;
193 198  
194 199 if (disk_read(startblock, getsize, bufptr) < 0) {
195 200 debug("Error reading FAT blocks\n");
... ... @@ -494,10 +499,8 @@
494 499 if (getsize > fatlength)
495 500 getsize = fatlength;
496 501  
497   - if (mydata->fatbufnum != -1) {
498   - if (flush_fat_buffer(mydata) < 0)
499   - return -1;
500   - }
  502 + if (flush_dirty_fat_buffer(mydata) < 0)
  503 + return -1;
501 504  
502 505 if (disk_read(startblock, getsize, bufptr) < 0) {
503 506 debug("Error reading FAT blocks\n");
... ... @@ -506,6 +509,9 @@
506 509 mydata->fatbufnum = bufnum;
507 510 }
508 511  
  512 + /* Mark as dirty */
  513 + mydata->fat_dirty = 1;
  514 +
509 515 /* Set the actual entry */
510 516 switch (mydata->fatsize) {
511 517 case 32:
... ... @@ -645,7 +651,7 @@
645 651  
646 652 dir_curclust = dir_newclust;
647 653  
648   - if (flush_fat_buffer(mydata) < 0)
  654 + if (flush_dirty_fat_buffer(mydata) < 0)
649 655 return;
650 656  
651 657 memset(get_dentfromdir_block, 0x00,
... ... @@ -675,7 +681,7 @@
675 681 }
676 682  
677 683 /* Flush fat buffer */
678   - if (flush_fat_buffer(mydata) < 0)
  684 + if (flush_dirty_fat_buffer(mydata) < 0)
679 685 return -1;
680 686  
681 687 return 0;
... ... @@ -1011,6 +1017,7 @@
1011 1017 }
1012 1018  
1013 1019 mydata->fatbufnum = -1;
  1020 + mydata->fat_dirty = 0;
1014 1021 mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
1015 1022 if (mydata->fatbuf == NULL) {
1016 1023 debug("Error: allocating memory\n");
... ... @@ -1111,7 +1118,7 @@
1111 1118 debug("attempt to write 0x%llx bytes\n", *actwrite);
1112 1119  
1113 1120 /* Flush fat buffer */
1114   - ret = flush_fat_buffer(mydata);
  1121 + ret = flush_dirty_fat_buffer(mydata);
1115 1122 if (ret) {
1116 1123 printf("Error: flush fat buffer\n");
1117 1124 goto exit;
... ... @@ -169,6 +169,7 @@
169 169 int fatsize; /* Size of FAT in bits */
170 170 __u32 fatlength; /* Length of FAT in sectors */
171 171 __u16 fat_sect; /* Starting sector of the FAT */
  172 + __u8 fat_dirty; /* Set if fatbuf has been modified */
172 173 __u32 rootdir_sect; /* Start sector of root directory */
173 174 __u16 sect_size; /* Size of sectors in bytes */
174 175 __u16 clust_size; /* Size of clusters in sectors */