Andriy Gapon wrote: > on 28/05/2008 12:02 Harti Brandt said the following: >> Hi all, >> >> it looks like there is no fallback in cp(1) when mmaping the source file >> fails. I'm mounting SMB shares via smbnetfs (which in turn uses fuse) >> and it seems not to support mmaping files. Shouldn't cp just fallback to >> a normal read()/write() loop in this case? > > I would think that it should. > This topic was brought up several times, but no resolution so far. > I think that I've even seen patches. > I've not seen the patches, but the fix is trivial (see the attached patch). If there are no objections, I can commit it. I also think we should use mmap for larger files, mmapping and writing them out in several chunks. Diomidis - dds_at_ Index: utils.c =================================================================== RCS file: /home/ncvs/src/bin/cp/utils.c,v retrieving revision 1.53 diff -u -r1.53 utils.c --- utils.c 10 Mar 2008 19:58:41 -0000 1.53 +++ utils.c 29 May 2008 20:39:38 -0000 _at__at_ -137,41 +137,39 _at__at_ * Mmap and write if less than 8M (the limit is so we don't totally * trash memory on big files. This is really a minor hack, but it * wins some CPU back. + * Some filesystems, such as smbnetfs, don't support mmap, + * so this is a best-effort attempt. */ #ifdef VM_AND_BUFFER_CACHE_SYNCHRONIZED if (S_ISREG(fs->st_mode) && fs->st_size > 0 && - fs->st_size <= 8 * 1048576) { - if ((p = mmap(NULL, (size_t)fs->st_size, PROT_READ, - MAP_SHARED, from_fd, (off_t)0)) == MAP_FAILED) { + fs->st_size <= 8 * 1048576 && + (p = mmap(NULL, (size_t)fs->st_size, PROT_READ, + MAP_SHARED, from_fd, (off_t)0)) != MAP_FAILED) { + wtotal = 0; + for (bufp = p, wresid = fs->st_size; ; + bufp += wcount, wresid -= (size_t)wcount) { + wcount = write(to_fd, bufp, wresid); + if (wcount <= 0) + break; + wtotal += wcount; + if (info) { + info = 0; + (void)fprintf(stderr, + "%s -> %s %3d%%\n", + entp->fts_path, to.p_path, + cp_pct(wtotal, fs->st_size)); + } + if (wcount >= (ssize_t)wresid) + break; + } + if (wcount != (ssize_t)wresid) { + warn("%s", to.p_path); + rval = 1; + } + /* Some systems don't unmap on close(2). */ + if (munmap(p, fs->st_size) < 0) { warn("%s", entp->fts_path); rval = 1; - } else { - wtotal = 0; - for (bufp = p, wresid = fs->st_size; ; - bufp += wcount, wresid -= (size_t)wcount) { - wcount = write(to_fd, bufp, wresid); - if (wcount <= 0) - break; - wtotal += wcount; - if (info) { - info = 0; - (void)fprintf(stderr, - "%s -> %s %3d%%\n", - entp->fts_path, to.p_path, - cp_pct(wtotal, fs->st_size)); - } - if (wcount >= (ssize_t)wresid) - break; - } - if (wcount != (ssize_t)wresid) { - warn("%s", to.p_path); - rval = 1; - } - /* Some systems don't unmap on close(2). */ - if (munmap(p, fs->st_size) < 0) { - warn("%s", entp->fts_path); - rval = 1; - } } } else #endifReceived on Thu May 29 2008 - 19:31:40 UTC
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