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Make fsck(8) use pread(2). This cuts the number of syscalls by half.

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Reviewed by:	kib, mckusick
MFC after:	2 weeks
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D17586
This commit is contained in:
Edward Tomasz Napierala 2018-12-15 11:36:20 +00:00
parent b329fb2885
commit 04e5c6f18a
1 changed files with 4 additions and 15 deletions
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19
sbin/fsck_ffs/fsutil.c
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@ -576,9 +576,7 @@ blread(int fd, char *buf, ufs2_daddr_t blk, long size)
slowio_start();
totalreads++;
diskreads++;
if (lseek(fd, offset, 0) < 0)
rwerror("SEEK BLK", blk);
else if (read(fd, buf, (int)size) == size) {
if (pread(fd, buf, (int)size, offset) == size) {
if (bkgrdflag)
slowio_end();
return (0);
@ -595,14 +593,11 @@ blread(int fd, char *buf, ufs2_daddr_t blk, long size)
} else
rwerror("READ BLK", blk);
if (lseek(fd, offset, 0) < 0)
rwerror("SEEK BLK", blk);
errs = 0;
memset(buf, 0, (size_t)size);
printf("THE FOLLOWING DISK SECTORS COULD NOT BE READ:");
for (cp = buf, i = 0; i < size; i += secsize, cp += secsize) {
if (read(fd, cp, (int)secsize) != secsize) {
(void)lseek(fd, offset + i + secsize, 0);
if (pread(fd, cp, (int)secsize, offset + i) != secsize) {
if (secsize != dev_bsize && dev_bsize != 1)
printf(" %jd (%jd),",
(intmax_t)(blk * dev_bsize + i) / secsize,
@ -629,22 +624,16 @@ blwrite(int fd, char *buf, ufs2_daddr_t blk, ssize_t size)
return;
offset = blk;
offset *= dev_bsize;
if (lseek(fd, offset, 0) < 0)
rwerror("SEEK BLK", blk);
else if (write(fd, buf, size) == size) {
if (pwrite(fd, buf, size, offset) == size) {
fsmodified = 1;
return;
}
resolved = 0;
rwerror("WRITE BLK", blk);
if (lseek(fd, offset, 0) < 0)
rwerror("SEEK BLK", blk);
printf("THE FOLLOWING SECTORS COULD NOT BE WRITTEN:");
for (cp = buf, i = 0; i < size; i += dev_bsize, cp += dev_bsize)
if (write(fd, cp, dev_bsize) != dev_bsize) {
(void)lseek(fd, offset + i + dev_bsize, 0);
if (pwrite(fd, cp, dev_bsize, offset + i) != dev_bsize)
printf(" %jd,", (intmax_t)blk + i / dev_bsize);
}
printf("\n");
return;
}