<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <style type="text/css" style="display:none;"> P {margin-top:0;margin-bottom:0;} </style> </head> <body dir="ltr"> <div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"> That's fine with me, thanks</div> <div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"> </div> <div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"> Simon</div> <div id="appendonsend"></div> <hr style="display:inline-block;width:98%" tabindex="-1"> <div id="divRplyFwdMsg" dir="ltr">From: Michal Prívozník <mprivozn@redhat.com> Sent: 24 August 2021 14:37 To: Simon Rowe <simon.rowe@nutanix.com>; libvir-list@redhat.com <libvir-list@redhat.com> Subject: Re: [PATCHv2 1/2] iohelper: skip lseek() and ftruncate() on block devices <div> </div> </div> <div class="BodyFragment"> <div class="PlainText">On 8/23/21 5:40 PM, Simon Rowe wrote: > Signed-off-by: Simon Rowe <simon.rowe@nutanix.com> > --- > 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); I think we can check for this before this switch() and report error if fstat() fails. That way we can .. > /* 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) { .. 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 </div> </div> </body> </html>