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On 06/25/2012 05:56 AM, Daniel P. Berrange wrote:
> On Fri, Jun 22, 2012 at 09:59:58AM -0400, Daniel J Walsh wrote: Currently
> libvirt-lxc checks to see if the destination exists and is a directory. If
> it is not a directory then the mount fails. Since libvirt-lxc can bind
> mount files on an inode, this patch is needed to allow us to bind mount
> files on files. Currently we want to bind mount on top of /etc/machine-id,
> and /etc/adjtime
>
> If the destination of the mount point does not exists, it checks if the src
> is a directory and then attempts to create a directory, otherwise it
> creates an empty file for the destination. The code will then bind mount
> over the destination.
>
> Current code blows up if the destination was not a directory. We want to
> be able to bind mount files on files.
>
> Sorry if you are seeing this patch for the second time, since I sent it to
> the wrong list.
>
>> diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c index
>> 24b1017..6cd8760 100644 --- a/src/lxc/lxc_container.c +++
>> b/src/lxc/lxc_container.c @@ -648,17 +665,37 @@ static int
>> lxcContainerMountFSBind(virDomainFSDefPtr fs, { char *src = NULL; int ret
>> = -1; + struct stat st;
>>
>> if (virAsprintf(&src, "%s%s", srcprefix, fs->src) < 0) {
>> virReportOOMError(); goto cleanup; }
>>
>> - if (virFileMakePath(fs->dst) < 0) { -
>> virReportSystemError(errno, - _("Failed to
>> create %s"), - fs->dst); - goto
>> cleanup; + if ((stat(fs->dst, &st) < 0) && (errno == ENOENT)) { +
>> if (stat(src, &st) >= 0) {
>
> We should be reporting errors if either of the stat() calls fails.
>
>> + if (S_ISDIR(st.st_mode)) { + if
>> (virFileMakePath(fs->dst) < 0) { +
>> virReportSystemError(errno, +
>> _("Failed to create %s"), +
>> fs->dst); + goto cleanup; + } +
>> } else { + /* Create Empty file for target mount point */
>> + int fd = open(fs->dst,
>> O_WRONLY|O_CREAT|O_NOCTTY|O_NONBLOCK, 0666); + if (fd >=
>> 0) { + close(fd);
>
> This needs to be VIR_CLOSE & have it exit stats checked, since close() can
> fail (particularly on NFS).
>
>> + } else { + if (errno != EEXIST) { +
>> virReportSystemError(errno, +
>> _("Failed to create %s"), +
>> fs->dst); + goto cleanup; + } +
>> } + } + }
>
>
> I'm applying the following variation on your patch which fixes the issues I
> mention above:
>
>
> - if (virFileMakePath(fs->dst) < 0) { -
> virReportSystemError(errno, - _("Failed to
> create %s"), - fs->dst); - goto
> cleanup; + if (stat(fs->dst, &st) < 0) { + if (errno != ENOENT)
> { + virReportSystemError(errno, _("Unable to stat bind target
> %s"), + fs->dst); + goto
> cleanup; + } + /* ENOENT => create the target dir or file */
> + if (stat(src, &st) < 0) { + virReportSystemError(errno,
> _("Unable to stat bind source %s"), +
> src); + goto cleanup; + } + if
> (S_ISDIR(st.st_mode)) { + if (virFileMakePath(fs->dst) < 0) { +
> virReportSystemError(errno, + _("Failed
> to create %s"), + fs->dst); +
> goto cleanup; + } + } else { + /* Create Empty
> file for target mount point */ + int fd = open(fs->dst,
> O_WRONLY|O_CREAT|O_NOCTTY|O_NONBLOCK, 0666); + if (fd < 0) { +
> if (errno != EEXIST) { + virReportSystemError(errno, +
> _("Failed to create bind target %s"), +
> fs->dst); + goto cleanup; + } +
> } + if (VIR_CLOSE(fd) < 0) { +
> virReportSystemError(errno, + _("Failed
> to close bind target %s"), + fs->dst);
> + goto cleanup; + } + }
>
>
> Daniel
>
Great thanks.
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