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Fix a bug with dirty file system handling.

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r356313 broke handling of dirty file system because we have restricted
the correction of "odd" byte sequences to checkfat(), and as a result
the dirty bit is never cleared.  The old fsck_msdosfs code would write
FAT twice to fix the dirty bit, which is also not ideal.

Fix this by introducing a new rountine, cleardirty() which will perform
the set of clean bit only, and use it in checkfilesys() if we thought
the file system was dirty.

Reviewed by:		cem, emaste
MFC after:		3 day
Differential Revision:	https://reviews.freebsd.org/D24581
This commit is contained in:
Xin LI 2020-04-27 02:01:48 +00:00
parent 258ba4c027
commit 401475f50c
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=360359
3 changed files with 50 additions and 2 deletions
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2
sbin/fsck_msdosfs/check.c
View File

@ -169,7 +169,7 @@ checkfilesys(const char *fname)
if (mod & FSDIRTY) {
pwarn("MARKING FILE SYSTEM CLEAN\n");
mod |= writefat(fat);
mod |= cleardirty(fat);
} else {
pwarn("\n***** FILE SYSTEM IS LEFT MARKED AS DIRTY *****\n");
mod |= FSERROR; /* file system not clean */

2
sbin/fsck_msdosfs/ext.h
View File

@ -90,6 +90,8 @@ int writefsinfo(int, struct bootblock *);
/* Opaque type */
struct fat_descriptor;
int cleardirty(struct fat_descriptor *);
void fat_clear_cl_head(struct fat_descriptor *, cl_t);
bool fat_is_cl_head(struct fat_descriptor *, cl_t);

48
sbin/fsck_msdosfs/fat.c
View File

@ -578,7 +578,6 @@ valid_cl(struct fat_descriptor *fat, cl_t cl)
* h = hard error flag (1 = ok; 0 = I/O error)
* x = any value ok
*/
int
checkdirty(int fs, struct bootblock *boot)
{
@ -642,6 +641,53 @@ checkdirty(int fs, struct bootblock *boot)
return ret;
}
int
cleardirty(struct fat_descriptor *fat)
{
int fd, ret = FSERROR;
struct bootblock *boot;
u_char *buffer;
size_t len;
off_t off;
boot = boot_of_(fat);
fd = fd_of_(fat);
if (boot->ClustMask != CLUST16_MASK && boot->ClustMask != CLUST32_MASK)
return 0;
off = boot->bpbResSectors;
off *= boot->bpbBytesPerSec;
buffer = malloc(len = boot->bpbBytesPerSec);
if (buffer == NULL) {
perr("No memory for FAT sectors (%zu)", len);
return 1;
}
if ((size_t)pread(fd, buffer, len, off) != len) {
perr("Unable to read FAT");
goto err;
}
if (boot->ClustMask == CLUST16_MASK) {
buffer[3] |= 0x80;
} else {
buffer[7] |= 0x08;
}
if ((size_t)pwrite(fd, buffer, len, off) != len) {
perr("Unable to write FAT");
goto err;
}
ret = FSOK;
err:
free(buffer);
return ret;
}
/*
* Read a FAT from disk. Returns 1 if successful, 0 otherwise.
*/