CC-tea/coreutils
1
0
Fork 0
mirror of git://git.sv.gnu.org/coreutils.git synced 2026-08-09 02:04:06 +02:00
Code Issues Projects Releases Wiki Activity

Enable direct-mode I/O (bypassing the buffer cache), if possible.

Browse Source 
Prompted by a suggestion from Kalle Olavi Niemitalo
in http://bugs.debian.org/207035.

(direct_mode): New function.
(do_wipefd): Turn on direct-mode I/O.
(dopass): If a file's first write fails with EINVAL,
turn off direct-mode I/O and retry the write.
This commit is contained in:
Jim Meyering
2004-06-07 15:27:42 +00:00
parent 8f3e7ea813
commit 16155336a0
1 changed files with 43 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/shred.c
+43 -1
View File
@@ -810,6 +810,31 @@ dosync (int fd, char const *qname)
return 0;
}
/* Turn on or off direct I/O mode for file descriptor FD, if possible.
Try to turn it on if ENABLE is true. Otherwise, try to turn it off. */
static void
direct_mode (int fd, bool enable)
{
if (O_DIRECT)
{
int fd_flags = fcntl (fd, F_GETFL);
if (0 < fd_flags)
{
int new_flags = (enable
? (fd_flags | O_DIRECT)
: (fd_flags & ~O_DIRECT));
if (new_flags != fd_flags)
fcntl (fd, F_SETFL, new_flags);
}
}
#if HAVE_DIRECTIO && defined DIRECTIO_ON
/* This is Solaris-specific. See the following for details:
http://docs.sun.com/db/doc/816-0213/6m6ne37so?q=directio&a=view */
directio (fd, DIRECTIO_ON);
#endif
}
/*
* Do pass number k of n, writing "size" bytes of the given pattern "type"
* to the file descriptor fd. Qname, k and n are passed in only for verbose
@@ -836,6 +861,7 @@ dopass (int fd, char const *qname, off_t *sizep, int type,
size_t ralign = lcm (getpagesize (), sizeof *r); /* Fill alignment. */
char pass_string[PASS_NAME_SIZE]; /* Name of current pass */
bool write_error = false;
bool first_write = true;
/* Printable previous offset into the file */
char previous_offset_buf[LONGEST_HUMAN_READABLE + 1];
@@ -890,7 +916,7 @@ dopass (int fd, char const *qname, off_t *sizep, int type,
if (type < 0)
fillrand (s, r, rsize, lim);
/* Loop to retry partial writes. */
for (soff = 0; soff < lim; soff += ssize)
for (soff = 0; soff < lim; soff += ssize, first_write = false)
{
ssize = write (fd, (char *) r + soff, lim - soff);
if (ssize <= 0)
@@ -906,6 +932,20 @@ dopass (int fd, char const *qname, off_t *sizep, int type,
{
int errnum = errno;
char buf[INT_BUFSIZE_BOUND (uintmax_t)];
/* If the first write of the first pass for a given file
has just failed with EINVAL, turn off direct mode I/O
and try again. This works around a bug in linux-2.4
whereby opening with O_DIRECT would succeed for some
file system types (e.g., ext3), but any attempt to
access a file through the resulting descriptor would
fail with EINVAL. */
if (k == 1 && first_write && errno == EINVAL)
{
direct_mode (fd, false);
ssize = 0;
continue;
}
error (0, errnum, _("%s: error writing at offset %s"),
qname, umaxtostr ((uintmax_t) offset + soff, buf));
/*
@@ -1243,6 +1283,8 @@ do_wipefd (int fd, char const *qname, struct isaac_state *s,
return false;
}
direct_mode (fd, true);
/* Allocate pass array */
passarray = xnmalloc (flags->n_iterations, sizeof *passarray);