Re: [libvirt RFCv4 01/20] iohelper: introduce new struct to carry copy operation parameters

this is in preparation for a minor refactoring of the copy function itself out of runIO(). Signed-off-by: Claudio Fontana <cfontana(a)suse.de&gt; --- src/util/iohelper.c | 95 +++++++++++++++++++++++++-------------------- 1 file changed, 53 insertions(+), 42 deletions(-) diff --git a/src/util/iohelper.c b/src/util/iohelper.c index 2c91bf4f93..c13746a547 100644 --- a/src/util/iohelper.c +++ b/src/util/iohelper.c @@ -45,6 +45,16 @@ # define O_DIRECT 0 #endif +struct runIOParams { + bool isBlockDev; + bool isDirect; + bool isWrite; + int fdin; + const char *fdinname; + int fdout; + const char *fdoutname; +}; + static int runIO(const char *path, int fd, int oflags) { @@ -53,13 +63,9 @@ runIO(const char *path, int fd, int oflags) size_t buflen = 1024*1024; intptr_t alignMask = 64*1024 - 1; int ret = -1; - int fdin, fdout; - const char *fdinname, *fdoutname; - unsigned long long total = 0; - bool direct = O_DIRECT && ((oflags & O_DIRECT) != 0); - off_t end = 0; + off_t total = 0; struct stat sb; - bool isBlockDev = false; + struct runIOParams p; #if WITH_POSIX_MEMALIGN if (posix_memalign(&base, alignMask + 1, buflen)) @@ -77,34 +83,23 @@ runIO(const char *path, int fd, int oflags) fd, path); goto cleanup; } - isBlockDev = S_ISBLK(sb.st_mode); + p.isBlockDev = S_ISBLK(sb.st_mode); + p.isDirect = O_DIRECT && (oflags & O_DIRECT); switch (oflags & O_ACCMODE) { case O_RDONLY: - fdin = fd; - fdinname = path; - fdout = STDOUT_FILENO; - fdoutname = "stdout"; - /* 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_CUR)) != 0)) { - virReportSystemError(end < 0 ? errno : EINVAL, "%s", - _("O_DIRECT read needs entire seekable file")); - goto cleanup; - } + p.isWrite = false; + p.fdin = fd; + p.fdinname = path; + p.fdout = STDOUT_FILENO; + p.fdoutname = "stdout"; break; case O_WRONLY: - fdin = STDIN_FILENO; - fdinname = "stdin"; - fdout = fd; - fdoutname = path; - /* 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) { - virReportSystemError(end < 0 ? errno : EINVAL, "%s", - _("O_DIRECT write needs empty seekable file")); - goto cleanup; - } + p.isWrite = true; + p.fdin = STDIN_FILENO; + p.fdinname = "stdin"; + p.fdout = fd; + p.fdoutname = path; break; case O_RDWR: @@ -114,6 +109,22 @@ runIO(const char *path, int fd, int oflags) (oflags & O_ACCMODE)); goto cleanup; } + /* To make the implementation simpler, we give up on any + * attempt to use O_DIRECT in a non-trivial manner. */ + if (!p.isBlockDev && p.isDirect) { + off_t off; + if (p.isWrite) { + if ((off = lseek(fd, 0, SEEK_END)) != 0) { + virReportSystemError(off < 0 ? errno : EINVAL, "%s", + _("O_DIRECT write needs empty seekable file")); + goto cleanup; + } + } else if ((off = lseek(fd, 0, SEEK_CUR)) != 0) { + virReportSystemError(off < 0 ? errno : EINVAL, "%s", + _("O_DIRECT read needs entire seekable file")); + goto cleanup; + }

+ } while (1) { ssize_t got; @@ -124,16 +135,16 @@ runIO(const char *path, int fd, int oflags) * writes will be aligned. * In other cases using saferead reduces number of syscalls. */ - if (fdin == fd && direct) { - if ((got = read(fdin, buf, buflen)) < 0 && + if (!p.isWrite && p.isDirect) { + if ((got = read(p.fdin, buf, buflen)) < 0 && errno == EINTR) continue; } else { - got = saferead(fdin, buf, buflen); + got = saferead(p.fdin, buf, buflen); }