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Fixed issue with committing directories to bad-blocks that are stuck

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This is only an issue in the weird case that are worn down block is
left in the odd state of not being able to change the data that resides
on the block. That being said, this does pop up often when simulating
wear on block devices.

Currently, directory commits checked if the write succeeded by crcing the
block to avoid the additional RAM cost for another buffer. However,
before this commit, directory commits just checked if the block crc was
valid, rather than comparing to the expected crc. This would usually
work, unless the block was stuck in a state with valid crc.

The fix is to simply compare with the expected crc to find errors.
This commit is contained in:
Christopher Haster
2017-11-16 14:53:45 -06:00
parent 3f31c8cba3
commit 6664723e18
3 changed files with 20 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
emubd/lfs_emubd.c
View File

@@ -138,8 +138,8 @@ int lfs_emubd_prog(const struct lfs_config *cfg, lfs_block_t block,
snprintf(emu->child, LFS_NAME_MAX, "%x", block); snprintf(emu->child, LFS_NAME_MAX, "%x", block);
FILE *f = fopen(emu->path, "r+b"); FILE *f = fopen(emu->path, "r+b");
if (!f && errno != ENOENT) { if (!f) {
return -errno; return (errno == EACCES) ? 0 : -errno;
} }
// Check that file was erased // Check that file was erased
@@ -189,14 +189,14 @@ int lfs_emubd_erase(const struct lfs_config *cfg, lfs_block_t block) {
return -errno; return -errno;
} }
if (!err && S_ISREG(st.st_mode)) { if (!err && S_ISREG(st.st_mode) && (S_IWUSR & st.st_mode)) {
int err = unlink(emu->path); int err = unlink(emu->path);
if (err) { if (err) {
return -errno; return -errno;
} }
} }
if (err || S_ISREG(st.st_mode)) { if (errno == ENOENT || (S_ISREG(st.st_mode) && (S_IWUSR & st.st_mode))) {
FILE *f = fopen(emu->path, "w"); FILE *f = fopen(emu->path, "w");
if (!f) { if (!f) {
return -errno; return -errno;

9
lfs.c
View File

@@ -531,18 +531,19 @@ static int lfs_dir_commit(lfs_t *lfs, lfs_dir_t *dir,
} }
// successful commit, check checksum to make sure // successful commit, check checksum to make sure
crc = 0xffffffff; uint32_t ncrc = 0xffffffff;
err = lfs_bd_crc(lfs, dir->pair[0], 0, err = lfs_bd_crc(lfs, dir->pair[0], 0,
0x7fffffff & dir->d.size, &crc); (0x7fffffff & dir->d.size)-4, &ncrc);
if (err) { if (err) {
return err; return err;
} }
if (crc == 0) { if (ncrc != crc) {
break; goto relocate;
} }
} }
break;
relocate: relocate:
//commit was corrupted //commit was corrupted
LFS_DEBUG("Bad block at %d", dir->pair[0]); LFS_DEBUG("Bad block at %d", dir->pair[0]);

11
tests/test_corrupt.sh
View File

@@ -82,6 +82,17 @@ do
lfs_chktree lfs_chktree
done done
echo "--- Block persistance ---"
for i in {0..33}
do
rm -rf blocks
mkdir blocks
lfs_mktree
chmod a-w blocks/$(printf '%x' $i)
lfs_mktree
lfs_chktree
done
echo "--- Big region corruption ---" echo "--- Big region corruption ---"
rm -rf blocks rm -rf blocks
mkdir blocks mkdir blocks