From 5ea96efaa0100e96b6b927eb1e67869143e1db4e Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 26 Sep 2017 13:42:53 -0400 Subject: [PATCH] Fix failure-to-read-man-page in commit 899bd785c. posix_fallocate() is not quite a drop-in replacement for fallocate(), because it is defined to return the error code as its function result, not in "errno". I (tgl) missed this because RHEL6's version seems to set errno as well. That is not the case on more modern Linuxen, though, as per buildfarm results. Aside from fixing the return-convention confusion, remove the test for ENOSYS; we expect that glibc will mask that for posix_fallocate, though it does not for fallocate. Keep the test for EINTR, because POSIX specifies that as a possible result, and buildfarm results suggest that it can happen in practice. Back-patch to 9.4, like the previous commit. Thomas Munro Discussion: https://postgr.es/m/1002664500.12301802.1471008223422.JavaMail.yahoo@mail.yahoo.com --- src/backend/storage/ipc/dsm_impl.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/src/backend/storage/ipc/dsm_impl.c b/src/backend/storage/ipc/dsm_impl.c index a5879060d0..b18bea64c6 100644 --- a/src/backend/storage/ipc/dsm_impl.c +++ b/src/backend/storage/ipc/dsm_impl.c @@ -425,17 +425,14 @@ dsm_impl_posix_resize(int fd, off_t size) do { rc = posix_fallocate(fd, 0, size); - } while (rc == -1 && errno == EINTR); + } while (rc == EINTR); - if (rc != 0 && errno == ENOSYS) - { - /* - * Kernel too old (< 2.6.23). Rather than fail, just trust that - * we won't hit the problem (it typically doesn't show up without - * many-GB-sized requests, anyway). - */ - rc = 0; - } + /* + * The caller expects errno to be set, but posix_fallocate() doesn't + * set it. Instead it returns error numbers directly. So set errno, + * even though we'll also return rc to indicate success or failure. + */ + errno = rc; } #endif /* HAVE_POSIX_FALLOCATE && __linux__ */ -- 2.40.0