From: Sean Finney Date: Tue, 19 Apr 2011 15:04:35 +0000 (-0400) Subject: nfs-utils: Increase the stdio file buffer size for procfs files X-Git-Tag: nfs-utils-1-2-4-rc8~1 X-Git-Url: https://git.decadent.org.uk/gitweb/?a=commitdiff_plain;h=5604b35a61e22930873ffc4e9971002f578e7978;p=nfs-utils.git nfs-utils: Increase the stdio file buffer size for procfs files Previously, when writing to /proc/net/rpc/*/channel, if a cache line were larger than the default buffer size (likely 1024 bytes), mountd and svcgssd would split writes into a number of buffer-sized writes. Each of these writes would get an EINVAL error back from the kernel procfs handle (it expects line-oriented input and does not account for multiple/split writes), and no cache update would occur. When such behavior occurs, NFS clients depending on mountd to finish the cache operation would block/hang, or receive EPERM, depending on the context of the operation. This is likely to happen if a user is a member of a large (~100-200) number of groups. Instead, every fopen() on the procfs files in question is followed by a call to setvbuf(), using a per-file dedicated buffer of RPC_CHAN_BUF_SIZE length. Really, mountd should not be using stdio-style buffered file operations on files in /proc to begin with. A better solution would be to use internally managed buffers and calls to write() instead of these stdio calls, but that would be a more extensive change; so this is proposed as a quick and not-so-dirty fix in the meantime. Signed-off-by: Sean Finney Signed-off-by: Steve Dickson --- diff --git a/support/include/misc.h b/support/include/misc.h index bc5ba23..eedc1fe 100644 --- a/support/include/misc.h +++ b/support/include/misc.h @@ -17,4 +17,7 @@ int weakrandomkey(unsigned char *keyout, int len); extern int is_mountpoint(char *path); +/* size of the file pointer buffers for rpc procfs files */ +#define RPC_CHAN_BUF_SIZE 32768 + #endif /* MISC_H */ diff --git a/utils/gssd/svcgssd_proc.c b/utils/gssd/svcgssd_proc.c index 7a916d7..c714d99 100644 --- a/utils/gssd/svcgssd_proc.c +++ b/utils/gssd/svcgssd_proc.c @@ -56,6 +56,7 @@ #include "gss_util.h" #include "err_util.h" #include "context.h" +#include "misc.h" #include "gss_oids.h" #include "svcgssd_krb5.h" @@ -71,6 +72,7 @@ struct svc_cred { int cr_ngroups; gid_t cr_groups[NGROUPS]; }; +static char vbuf[RPC_CHAN_BUF_SIZE]; static int do_svc_downcall(gss_buffer_desc *out_handle, struct svc_cred *cred, @@ -92,6 +94,7 @@ do_svc_downcall(gss_buffer_desc *out_handle, struct svc_cred *cred, SVCGSSD_CONTEXT_CHANNEL, strerror(errno)); goto out_err; } + setvbuf(f, vbuf, _IOLBF, RPC_CHAN_BUF_SIZE); qword_printhex(f, out_handle->value, out_handle->length); /* XXX are types OK for the rest of this? */ /* For context cache, use the actual context endtime */ diff --git a/utils/mountd/cache.c b/utils/mountd/cache.c index ce93e3c..df6b38f 100644 --- a/utils/mountd/cache.c +++ b/utils/mountd/cache.c @@ -825,6 +825,7 @@ struct { char *cache_name; void (*cache_handle)(FILE *f); FILE *f; + char vbuf[RPC_CHAN_BUF_SIZE]; } cachelist[] = { { "auth.unix.ip", auth_unix_ip, NULL}, { "auth.unix.gid", auth_unix_gid, NULL}, @@ -848,6 +849,10 @@ void cache_open(void) continue; sprintf(path, "/proc/net/rpc/%s/channel", cachelist[i].cache_name); cachelist[i].f = fopen(path, "r+"); + if (cachelist[i].f != NULL) { + setvbuf(cachelist[i].f, cachelist[i].vbuf, _IOLBF, + RPC_CHAN_BUF_SIZE); + } } }