Signed-off-by: Simon Rowe <simon.rowe(a)nutanix.com&gt; --- src/util/iohelper.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/src/util/iohelper.c b/src/util/iohelper.c index b8810d16d3..e6eb178fde 100644 --- a/src/util/iohelper.c +++ b/src/util/iohelper.c @@ -28,6 +28,8 @@ #include <unistd.h> #include <fcntl.h> #include <stdlib.h> +#include <sys/types.h> +#include <sys/stat.h> #include "virthread.h" #include "virfile.h" @@ -56,6 +58,8 @@ runIO(const char *path, int fd, int oflags) unsigned long long total = 0; bool direct = O_DIRECT && ((oflags & O_DIRECT) != 0); off_t end = 0; + struct stat sb; + bool isBlockDev = false; #if WITH_POSIX_MEMALIGN if (posix_memalign(&base, alignMask + 1, buflen)) @@ -86,9 +90,11 @@ runIO(const char *path, int fd, int oflags) fdinname = "stdin"; fdout = fd; fdoutname = path; + if (fstat(fd, &sb) == 0) + isBlockDev = S_ISBLK(sb.st_mode); /* To make the implementation simpler, we give up on any * attempt to use O_DIRECT in a non-trivial manner. */ - if (direct && (end = lseek(fd, 0, SEEK_END)) != 0) { + if (!isBlockDev && direct && (end = lseek(fd, 0, SEEK_END)) != 0) { virReportSystemError(end < 0 ? errno : EINVAL, "%s", _("O_DIRECT write needs empty seekable file")); goto cleanup; @@ -140,7 +146,7 @@ runIO(const char *path, int fd, int oflags) goto cleanup; } - if (ftruncate(fd, total) < 0) { + if (!isBlockDev && ftruncate(fd, total) < 0) { virReportSystemError(errno, _("Unable to truncate %s"), fdoutname); goto cleanup; } -- 2.22.3

That's fine with me, thanks Simon ________________________________ From: Michal Prívozník <mprivozn(a)redhat.com&gt; Sent: 24 August 2021 14:37 To: Simon Rowe <simon.rowe(a)nutanix.com>; libvir-list(a)redhat.com <libvir-list(a)redhat.com&gt; Subject: Re: [PATCHv2 1/2] iohelper: skip lseek() and ftruncate() on block devices On 8/23/21 5:40 PM, Simon Rowe wrote: I think we can check for this before this switch() and report error if fstat() fails. That way we can .. .. do this change for O_RDONLY case too. IOW, I suggest squashing this in: diff --git i/src/util/iohelper.c w/src/util/iohelper.c index e6eb178fde..2c91bf4f93 100644 --- i/src/util/iohelper.c +++ w/src/util/iohelper.c @@ -71,6 +71,14 @@ runIO(const char *path, int fd, int oflags) buf = (char *) (((intptr_t) base + alignMask) & ~alignMask); #endif + if (fstat(fd, &sb) < 0) { + virReportSystemError(errno, + _("Unable to access file descriptor %d path %s"), + fd, path); + goto cleanup; + } + isBlockDev = S_ISBLK(sb.st_mode); + switch (oflags & O_ACCMODE) { case O_RDONLY: fdin = fd; @@ -79,7 +87,7 @@ runIO(const char *path, int fd, int oflags) fdoutname = "stdout"; /* To make the implementation simpler, we give up on any * attempt to use O_DIRECT in a non-trivial manner. */ - if (direct && ((end = lseek(fd, 0, SEEK_CUR)) != 0)) { + if (!isBlockDev && direct && ((end = lseek(fd, 0, SEEK_CUR)) != 0)) { virReportSystemError(end < 0 ? errno : EINVAL, "%s", _("O_DIRECT read needs entire seekable file")); goto cleanup; @@ -90,8 +98,6 @@ runIO(const char *path, int fd, int oflags) fdinname = "stdin"; fdout = fd; fdoutname = path; - if (fstat(fd, &sb) == 0) - isBlockDev = S_ISBLK(sb.st_mode); /* To make the implementation simpler, we give up on any * attempt to use O_DIRECT in a non-trivial manner. */ if (!isBlockDev && direct && (end = lseek(fd, 0, SEEK_END)) != 0) { No need to resend, just let me know if you're okay with the suggested change and I'll squash it in before pushing. Michal