| Message ID | 20121213112529.06ebda22@notabene.brown (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Dec 13, 2012 at 11:25:29AM +1100, NeilBrown wrote: > > > commit 5604b35a61e22930873ffc4e9971002f578e7978 > nfs-utils: Increase the stdio file buffer size for procfs files > > changed writes to some sysfs files to be line buffered (_IOLBF) where > they weren't before. While this probably makes sense, it introduced a bug. > > With fully buffered streams, you don't expect to get an error until you > call fflush(). > With line buffered streams you can get the error from fprintf() et al. > > qword_eol() only tests the return from fflush(), not from fprintf(). Consequently > errors were not noticed. > > One result of this is that if you export, with crossmnt, a filesystem underneath > which are mounted non-exportable filesystems (e.g. /proc) then an 'ls -l' on the > client will block indefinitely waiting for a meaningful 'yes' or 'no' from the > server, but will never get one. > > This patch changes qword_eol to test both fprintf and fflush. Makes sense to me.--b. > > Signed-off-by: NeilBrown <neilb@suse.de> > > diff --git a/support/nfs/cacheio.c b/support/nfs/cacheio.c > index e641c45..61e07a8 100644 > --- a/support/nfs/cacheio.c > +++ b/support/nfs/cacheio.c > @@ -162,11 +162,16 @@ int qword_eol(FILE *f) > { > int err; > > - fprintf(f,"\n"); > - err = fflush(f); > - if (err) { > - xlog_warn("qword_eol: fflush failed: errno %d (%s)", > + err = fprintf(f,"\n"); > + if (err < 0) { > + xlog_warn("qword_eol: fprintf failed: errno %d (%s)", > errno, strerror(errno)); > + } else { > + err = fflush(f); > + if (err) { > + xlog_warn("qword_eol: fflush failed: errno %d (%s)", > + errno, strerror(errno)); > + } > } > /* > * We must send one line (and one line only) in a single write -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 12/12/12 19:25, NeilBrown wrote: > > > commit 5604b35a61e22930873ffc4e9971002f578e7978 > nfs-utils: Increase the stdio file buffer size for procfs files > > changed writes to some sysfs files to be line buffered (_IOLBF) where > they weren't before. While this probably makes sense, it introduced a bug. > > With fully buffered streams, you don't expect to get an error until you > call fflush(). > With line buffered streams you can get the error from fprintf() et al. > > qword_eol() only tests the return from fflush(), not from fprintf(). Consequently > errors were not noticed. > > One result of this is that if you export, with crossmnt, a filesystem underneath > which are mounted non-exportable filesystems (e.g. /proc) then an 'ls -l' on the > client will block indefinitely waiting for a meaningful 'yes' or 'no' from the > server, but will never get one. > > This patch changes qword_eol to test both fprintf and fflush. > > Signed-off-by: NeilBrown <neilb@suse.de> Committed... steved. > > diff --git a/support/nfs/cacheio.c b/support/nfs/cacheio.c > index e641c45..61e07a8 100644 > --- a/support/nfs/cacheio.c > +++ b/support/nfs/cacheio.c > @@ -162,11 +162,16 @@ int qword_eol(FILE *f) > { > int err; > > - fprintf(f,"\n"); > - err = fflush(f); > - if (err) { > - xlog_warn("qword_eol: fflush failed: errno %d (%s)", > + err = fprintf(f,"\n"); > + if (err < 0) { > + xlog_warn("qword_eol: fprintf failed: errno %d (%s)", > errno, strerror(errno)); > + } else { > + err = fflush(f); > + if (err) { > + xlog_warn("qword_eol: fflush failed: errno %d (%s)", > + errno, strerror(errno)); > + } > } > /* > * We must send one line (and one line only) in a single write > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/support/nfs/cacheio.c b/support/nfs/cacheio.c index e641c45..61e07a8 100644 --- a/support/nfs/cacheio.c +++ b/support/nfs/cacheio.c @@ -162,11 +162,16 @@ int qword_eol(FILE *f) { int err; - fprintf(f,"\n"); - err = fflush(f); - if (err) { - xlog_warn("qword_eol: fflush failed: errno %d (%s)", + err = fprintf(f,"\n"); + if (err < 0) { + xlog_warn("qword_eol: fprintf failed: errno %d (%s)", errno, strerror(errno)); + } else { + err = fflush(f); + if (err) { + xlog_warn("qword_eol: fflush failed: errno %d (%s)", + errno, strerror(errno)); + } } /* * We must send one line (and one line only) in a single write
commit 5604b35a61e22930873ffc4e9971002f578e7978 nfs-utils: Increase the stdio file buffer size for procfs files changed writes to some sysfs files to be line buffered (_IOLBF) where they weren't before. While this probably makes sense, it introduced a bug. With fully buffered streams, you don't expect to get an error until you call fflush(). With line buffered streams you can get the error from fprintf() et al. qword_eol() only tests the return from fflush(), not from fprintf(). Consequently errors were not noticed. One result of this is that if you export, with crossmnt, a filesystem underneath which are mounted non-exportable filesystems (e.g. /proc) then an 'ls -l' on the client will block indefinitely waiting for a meaningful 'yes' or 'no' from the server, but will never get one. This patch changes qword_eol to test both fprintf and fflush. Signed-off-by: NeilBrown <neilb@suse.de>