Re: [PATCH 1/4] xfs_restore: refactor open-coded file creation code

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Mon, May 06, 2019 at 05:11:23PM -0700, Allison Collins wrote:
> On 2/22/19 9:47 AM, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Create a helper to unlink, recreate, and reserve space in a file so that
> > we don't have two open-coded versions.  We lose the broken ALLOCSP code
> > since it never worked anyway.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >   restore/dirattr.c |   97 ++++++++++++++++++-----------------------------------
> >   restore/dirattr.h |    2 +
> >   restore/namreg.c  |   70 +++-----------------------------------
> >   3 files changed, 41 insertions(+), 128 deletions(-)
> > 
> > 
> > diff --git a/restore/dirattr.c b/restore/dirattr.c
> > index 5368664..0fb2877 100644
> > --- a/restore/dirattr.c
> > +++ b/restore/dirattr.c
> > @@ -55,6 +55,37 @@
> >   #include "openutil.h"
> >   #include "mmap.h"
> > +/* Create a file, try to reserve space for it, and return the fd. */
> > +int
> > +create_filled_file(
> > +	const char	*pathname,
> > +	off64_t		size)
> > +{
> > +	struct flock64	fl = {
> > +		.l_len = size,
> > +	};
> > +	int		fd;
> > +	int		ret;
> > +
> > +	(void)unlink(pathname);
> > +
> > +	fd = open(pathname, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
> > +	if (fd < 0)
> > +		return fd;
> 
> Just a nit: I think if you goto done here instead of return, you can remove
> the extra goto below since it's not having much effect.  I sort of figured
> people like gotos because they like having one exit point to the function.
> Alternatively, if you don't mind having multiple exit points, you can simply
> return early in patch 4, and avoid the goto all together.

Hmm, you're right, let's just return fd directly instead of all this
goto nonsense.

--D

> Allison
> 
> > +
> > +	ret = ioctl(fd, XFS_IOC_RESVSP64, &fl);
> > +	if (ret && errno != ENOTTY)
> > +		mlog(MLOG_VERBOSE | MLOG_NOTE,
> > +_("attempt to reserve %lld bytes for %s using %s failed: %s (%d)\n"),
> > +				size, pathname, "XFS_IOC_RESVSP64",
> > +				strerror(errno), errno);
> > +	if (ret == 0)
> > +		goto done;
> > +
> > +done:
> > +	return fd;
> > +}
> > +
> >   /* structure definitions used locally ****************************************/
> >   /* node handle limits
> > @@ -238,13 +269,8 @@ dirattr_init(char *hkdir, bool_t resume, uint64_t dircnt)
> >   			return BOOL_FALSE;
> >   		}
> >   	} else {
> > -		/* create the dirattr file, first unlinking any older version
> > -		 * laying around
> > -		 */
> > -		(void)unlink(dtp->dt_pathname);
> > -		dtp->dt_fd = open(dtp->dt_pathname,
> > -				   O_RDWR | O_CREAT | O_EXCL,
> > -				   S_IRUSR | S_IWUSR);
> > +		dtp->dt_fd = create_filled_file(dtp->dt_pathname,
> > +			DIRATTR_PERS_SZ + (dircnt * sizeof(struct dirattr)));
> >   		if (dtp->dt_fd < 0) {
> >   			mlog(MLOG_NORMAL | MLOG_ERROR, _(
> >   			      "could not create directory attributes file %s: "
> > @@ -253,63 +279,6 @@ dirattr_init(char *hkdir, bool_t resume, uint64_t dircnt)
> >   			      strerror(errno));
> >   			return BOOL_FALSE;
> >   		}
> > -
> > -		/* reserve space for the backing store. try to use RESVSP64.
> > -		 * if doesn't work, try ALLOCSP64. the former is faster, as
> > -		 * it does not zero the space.
> > -		 */
> > -		{
> > -		bool_t successpr;
> > -		unsigned int ioctlcmd;
> > -		int loglevel;
> > -		size_t trycnt;
> > -
> > -		for (trycnt = 0,
> > -		      successpr = BOOL_FALSE,
> > -		      ioctlcmd = XFS_IOC_RESVSP64,
> > -		      loglevel = MLOG_VERBOSE
> > -		      ;
> > -		      ! successpr && trycnt < 2
> > -		      ;
> > -		      trycnt++,
> > -		      ioctlcmd = XFS_IOC_ALLOCSP64,
> > -		      loglevel = max(MLOG_NORMAL, loglevel - 1)) {
> > -			off64_t initsz;
> > -			struct flock64 flock64;
> > -			int rval;
> > -
> > -			if (! ioctlcmd) {
> > -				continue;
> > -			}
> > -
> > -			initsz = (off64_t)DIRATTR_PERS_SZ
> > -				 +
> > -				 ((off64_t)dircnt * sizeof(dirattr_t));
> > -			flock64.l_whence = 0;
> > -			flock64.l_start = 0;
> > -			flock64.l_len = initsz;
> > -			rval = ioctl(dtp->dt_fd, ioctlcmd, &flock64);
> > -			if (rval) {
> > -				if (errno != ENOTTY) {
> > -					mlog(loglevel | MLOG_NOTE, _(
> > -					      "attempt to reserve %lld bytes for %s "
> > -					      "using %s "
> > -					      "failed: %s (%d)\n"),
> > -					      initsz,
> > -					      dtp->dt_pathname,
> > -					      ioctlcmd == XFS_IOC_RESVSP64
> > -					      ?
> > -					      "XFS_IOC_RESVSP64"
> > -					      :
> > -					      "XFS_IOC_ALLOCSP64",
> > -					      strerror(errno),
> > -					      errno);
> > -				}
> > -			} else {
> > -				successpr = BOOL_TRUE;
> > -			}
> > -		}
> > -		}
> >   	}
> >   	/* mmap the persistent descriptor
> > diff --git a/restore/dirattr.h b/restore/dirattr.h
> > index dd37a98..e81e69c 100644
> > --- a/restore/dirattr.h
> > +++ b/restore/dirattr.h
> > @@ -88,4 +88,6 @@ extern bool_t dirattr_cb_extattr(dah_t dah,
> >   				  extattrhdr_t *ahdrp,
> >   				  void *ctxp);
> > +int create_filled_file(const char *pathname, off64_t size);
> > +
> >   #endif /* DIRATTR_H */
> > diff --git a/restore/namreg.c b/restore/namreg.c
> > index 89fa5ef..d0d5e89 100644
> > --- a/restore/namreg.c
> > +++ b/restore/namreg.c
> > @@ -37,6 +37,10 @@
> >   #include "namreg.h"
> >   #include "openutil.h"
> >   #include "mmap.h"
> > +#include "global.h"
> > +#include "content.h"
> > +#include "content_inode.h"
> > +#include "dirattr.h"
> >   /* structure definitions used locally ****************************************/
> > @@ -153,13 +157,8 @@ namreg_init(char *hkdir, bool_t resume, uint64_t inocnt)
> >   			return BOOL_FALSE;
> >   		}
> >   	} else {
> > -		/* create the namreg file, first unlinking any older version
> > -		 * laying around
> > -		 */
> > -		(void)unlink(ntp->nt_pathname);
> > -		ntp->nt_fd = open(ntp->nt_pathname,
> > -				   O_RDWR | O_CREAT | O_EXCL,
> > -				   S_IRUSR | S_IWUSR);
> > +		ntp->nt_fd = create_filled_file(ntp->nt_pathname,
> > +			NAMREG_PERS_SZ + (inocnt * NAMREG_AVGLEN));
> >   		if (ntp->nt_fd < 0) {
> >   			mlog(MLOG_NORMAL | MLOG_ERROR, _(
> >   			      "could not create name registry file %s: "
> > @@ -168,63 +167,6 @@ namreg_init(char *hkdir, bool_t resume, uint64_t inocnt)
> >   			      strerror(errno));
> >   			return BOOL_FALSE;
> >   		}
> > -
> > -		/* reserve space for the backing store. try to use RESVSP64.
> > -		 * if doesn't work, try ALLOCSP64. the former is faster, as
> > -		 * it does not zero the space.
> > -		 */
> > -		{
> > -		bool_t successpr;
> > -		unsigned int ioctlcmd;
> > -		int loglevel;
> > -		size_t trycnt;
> > -
> > -		for (trycnt = 0,
> > -		      successpr = BOOL_FALSE,
> > -		      ioctlcmd = XFS_IOC_RESVSP64,
> > -		      loglevel = MLOG_VERBOSE
> > -		      ;
> > -		      ! successpr && trycnt < 2
> > -		      ;
> > -		      trycnt++,
> > -		      ioctlcmd = XFS_IOC_ALLOCSP64,
> > -		      loglevel = max(MLOG_NORMAL, loglevel - 1)) {
> > -			off64_t initsz;
> > -			struct flock64 flock64;
> > -			int rval;
> > -
> > -			if (! ioctlcmd) {
> > -				continue;
> > -			}
> > -
> > -			initsz = (off64_t)NAMREG_PERS_SZ
> > -				 +
> > -				 ((off64_t)inocnt * NAMREG_AVGLEN);
> > -			flock64.l_whence = 0;
> > -			flock64.l_start = 0;
> > -			flock64.l_len = initsz;
> > -			rval = ioctl(ntp->nt_fd, ioctlcmd, &flock64);
> > -			if (rval) {
> > -				if (errno != ENOTTY) {
> > -					mlog(loglevel | MLOG_NOTE, _(
> > -					      "attempt to reserve %lld bytes for %s "
> > -					      "using %s "
> > -					      "failed: %s (%d)\n"),
> > -					      initsz,
> > -					      ntp->nt_pathname,
> > -					      ioctlcmd == XFS_IOC_RESVSP64
> > -					      ?
> > -					      "XFS_IOC_RESVSP64"
> > -					      :
> > -					      "XFS_IOC_ALLOCSP64",
> > -					      strerror(errno),
> > -					      errno);
> > -				}
> > -			} else {
> > -				successpr = BOOL_TRUE;
> > -			}
> > -		}
> > -		}
> >   	}
> >   	/* mmap the persistent descriptor
> >