[10/11] xfs: make xfs_*read_agf return EAGAIN to ALLOC_FLAG_TRYLOCK callers
diff mbox series

Message ID 157924228165.3029431.1835481566077971155.stgit@magnolia
State New
Headers show
Series
  • xfs: make buffer functions return error codes
Related show

Commit Message

Darrick J. Wong Jan. 17, 2020, 6:24 a.m. UTC
From: Darrick J. Wong <darrick.wong@oracle.com>

Refactor xfs_read_agf and xfs_alloc_read_agf to return EAGAIN if the
caller passed TRYLOCK and we weren't able to get the lock; and change
the callers to recognize this.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_alloc.c |   31 +++++++++++++++----------------
 fs/xfs/libxfs/xfs_bmap.c  |    9 +++++----
 fs/xfs/xfs_filestream.c   |   11 ++++++-----
 3 files changed, 26 insertions(+), 25 deletions(-)

Comments

Christoph Hellwig Jan. 17, 2020, 6:59 a.m. UTC | #1
On Thu, Jan 16, 2020 at 10:24:41PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Refactor xfs_read_agf and xfs_alloc_read_agf to return EAGAIN if the
> caller passed TRYLOCK and we weren't able to get the lock; and change
> the callers to recognize this.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_alloc.c |   31 +++++++++++++++----------------
>  fs/xfs/libxfs/xfs_bmap.c  |    9 +++++----
>  fs/xfs/xfs_filestream.c   |   11 ++++++-----
>  3 files changed, 26 insertions(+), 25 deletions(-)
> 
> 
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index 83273975df77..26f3e4db84e0 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -2502,13 +2502,15 @@ xfs_alloc_fix_freelist(
>  
>  	if (!pag->pagf_init) {
>  		error = xfs_alloc_read_agf(mp, tp, args->agno, flags, &agbp);
> -		if (error)
> -			goto out_no_agbp;
> -		if (!pag->pagf_init) {
> +		if (error == -EAGAIN) {
> +			/* Couldn't lock the AGF so skip this AG. */
>  			ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
>  			ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
> -			goto out_agbp_relse;
> +			error = 0;
> +			goto out_no_agbp;
>  		}
> +		if (error)
> +			goto out_no_agbp;

I wonder if something like:

		if (error) {
			if (error == -EAGAIN) {
				/* Couldn't lock the AGF so skip this AG. */
	 			ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
	 			ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
				error = 0;
			}
			goto out_no_agbp;
		}

would be a little nicer here?

> @@ -2533,13 +2535,15 @@ xfs_alloc_fix_freelist(
>  	 */
>  	if (!agbp) {
>  		error = xfs_alloc_read_agf(mp, tp, args->agno, flags, &agbp);
> -		if (error)
> -			goto out_no_agbp;
> -		if (!agbp) {
> +		if (error == -EAGAIN) {
> +			/* Couldn't lock the AGF so skip this AG. */
>  			ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
>  			ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
> +			error = 0;
>  			goto out_no_agbp;
>  		}
> +		if (error)
> +			goto out_no_agbp;
>  	}

Same here.  Also shouldn't those asserts just move into
xfs_alloc_read_agf or go away now that we have a proper return value
and not the magic NULL buffer?

> +	error = xfs_alloc_read_agf(mp, tp, agno, flags, &bp);
> +	if (error)
>  		return error;
> +	xfs_trans_brelse(tp, bp);
>  	return 0;

Maybe simplify this further to:

	error = xfs_alloc_read_agf(mp, tp, agno, flags, &bp);
	if (!error)
		xfs_trans_brelse(tp, bp);
	return error;

> @@ -2958,12 +2962,9 @@ xfs_read_agf(
>  	trace_xfs_read_agf(mp, agno);
>  
>  	ASSERT(agno != NULLAGNUMBER);
> -	error = xfs_trans_read_buf(
> -			mp, tp, mp->m_ddev_targp,
> +	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,

This hunk should probably go into the patch that changed the
xfs_trans_read_buf return value instead.

> +		if (error == -EAGAIN) {
> +			/* Couldn't lock the AGF, so skip this AG. */
>  			*notinit = 1;
> +			error = 0;
>  			goto out;
>  		}
> +		if (error)
> +			goto out;

Should probably be:

		if (error) {
			if (error == -EAGAIN) {
				/* Couldn't lock the AGF, so skip this AG. */
	 			*notinit = 1;
				error = 0;
			}
 			goto out;
Darrick J. Wong Jan. 17, 2020, 11:05 p.m. UTC | #2
On Thu, Jan 16, 2020 at 10:59:57PM -0800, Christoph Hellwig wrote:
> On Thu, Jan 16, 2020 at 10:24:41PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Refactor xfs_read_agf and xfs_alloc_read_agf to return EAGAIN if the
> > caller passed TRYLOCK and we weren't able to get the lock; and change
> > the callers to recognize this.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  fs/xfs/libxfs/xfs_alloc.c |   31 +++++++++++++++----------------
> >  fs/xfs/libxfs/xfs_bmap.c  |    9 +++++----
> >  fs/xfs/xfs_filestream.c   |   11 ++++++-----
> >  3 files changed, 26 insertions(+), 25 deletions(-)
> > 
> > 
> > diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> > index 83273975df77..26f3e4db84e0 100644
> > --- a/fs/xfs/libxfs/xfs_alloc.c
> > +++ b/fs/xfs/libxfs/xfs_alloc.c
> > @@ -2502,13 +2502,15 @@ xfs_alloc_fix_freelist(
> >  
> >  	if (!pag->pagf_init) {
> >  		error = xfs_alloc_read_agf(mp, tp, args->agno, flags, &agbp);
> > -		if (error)
> > -			goto out_no_agbp;
> > -		if (!pag->pagf_init) {
> > +		if (error == -EAGAIN) {
> > +			/* Couldn't lock the AGF so skip this AG. */
> >  			ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
> >  			ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
> > -			goto out_agbp_relse;
> > +			error = 0;
> > +			goto out_no_agbp;
> >  		}
> > +		if (error)
> > +			goto out_no_agbp;
> 
> I wonder if something like:
> 
> 		if (error) {
> 			if (error == -EAGAIN) {
> 				/* Couldn't lock the AGF so skip this AG. */
> 	 			ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
> 	 			ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
> 				error = 0;
> 			}
> 			goto out_no_agbp;
> 		}
> 
> would be a little nicer here?

> > @@ -2533,13 +2535,15 @@ xfs_alloc_fix_freelist(
> >  	 */
> >  	if (!agbp) {
> >  		error = xfs_alloc_read_agf(mp, tp, args->agno, flags, &agbp);
> > -		if (error)
> > -			goto out_no_agbp;
> > -		if (!agbp) {
> > +		if (error == -EAGAIN) {
> > +			/* Couldn't lock the AGF so skip this AG. */
> >  			ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
> >  			ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
> > +			error = 0;
> >  			goto out_no_agbp;
> >  		}
> > +		if (error)
> > +			goto out_no_agbp;
> >  	}
> 
> Same here.  Also shouldn't those asserts just move into
> xfs_alloc_read_agf or go away now that we have a proper return value
> and not the magic NULL buffer?

I'll move the assert into xfs_alloc_read_agf, so these all turn into:

if (error) {
	if (error == -EAGAIN)
		error = 0;
	goto next ag;
}

> 
> > +	error = xfs_alloc_read_agf(mp, tp, agno, flags, &bp);
> > +	if (error)
> >  		return error;
> > +	xfs_trans_brelse(tp, bp);
> >  	return 0;
> 
> Maybe simplify this further to:
> 
> 	error = xfs_alloc_read_agf(mp, tp, agno, flags, &bp);
> 	if (!error)
> 		xfs_trans_brelse(tp, bp);
> 	return error;

Ok.

> > @@ -2958,12 +2962,9 @@ xfs_read_agf(
> >  	trace_xfs_read_agf(mp, agno);
> >  
> >  	ASSERT(agno != NULLAGNUMBER);
> > -	error = xfs_trans_read_buf(
> > -			mp, tp, mp->m_ddev_targp,
> > +	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
> 
> This hunk should probably go into the patch that changed the
> xfs_trans_read_buf return value instead.

Ok.

> > +		if (error == -EAGAIN) {
> > +			/* Couldn't lock the AGF, so skip this AG. */
> >  			*notinit = 1;
> > +			error = 0;
> >  			goto out;
> >  		}
> > +		if (error)
> > +			goto out;
> 
> Should probably be:
> 
> 		if (error) {
> 			if (error == -EAGAIN) {
> 				/* Couldn't lock the AGF, so skip this AG. */
> 	 			*notinit = 1;
> 				error = 0;
> 			}
>  			goto out;

Fixed.

--D

Patch
diff mbox series

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 83273975df77..26f3e4db84e0 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2502,13 +2502,15 @@  xfs_alloc_fix_freelist(
 
 	if (!pag->pagf_init) {
 		error = xfs_alloc_read_agf(mp, tp, args->agno, flags, &agbp);
-		if (error)
-			goto out_no_agbp;
-		if (!pag->pagf_init) {
+		if (error == -EAGAIN) {
+			/* Couldn't lock the AGF so skip this AG. */
 			ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
 			ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
-			goto out_agbp_relse;
+			error = 0;
+			goto out_no_agbp;
 		}
+		if (error)
+			goto out_no_agbp;
 	}
 
 	/*
@@ -2533,13 +2535,15 @@  xfs_alloc_fix_freelist(
 	 */
 	if (!agbp) {
 		error = xfs_alloc_read_agf(mp, tp, args->agno, flags, &agbp);
-		if (error)
-			goto out_no_agbp;
-		if (!agbp) {
+		if (error == -EAGAIN) {
+			/* Couldn't lock the AGF so skip this AG. */
 			ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
 			ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
+			error = 0;
 			goto out_no_agbp;
 		}
+		if (error)
+			goto out_no_agbp;
 	}
 
 	/* reset a padding mismatched agfl before final free space check */
@@ -2768,10 +2772,10 @@  xfs_alloc_pagf_init(
 	xfs_buf_t		*bp;
 	int			error;
 
-	if ((error = xfs_alloc_read_agf(mp, tp, agno, flags, &bp)))
+	error = xfs_alloc_read_agf(mp, tp, agno, flags, &bp);
+	if (error)
 		return error;
-	if (bp)
-		xfs_trans_brelse(tp, bp);
+	xfs_trans_brelse(tp, bp);
 	return 0;
 }
 
@@ -2958,12 +2962,9 @@  xfs_read_agf(
 	trace_xfs_read_agf(mp, agno);
 
 	ASSERT(agno != NULLAGNUMBER);
-	error = xfs_trans_read_buf(
-			mp, tp, mp->m_ddev_targp,
+	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
 			XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
 			XFS_FSS_TO_BB(mp, 1), flags, bpp, &xfs_agf_buf_ops);
-	if (error == -EAGAIN)
-		return 0;
 	if (error)
 		return error;
 
@@ -2995,8 +2996,6 @@  xfs_alloc_read_agf(
 			bpp);
 	if (error)
 		return error;
-	if (!*bpp)
-		return 0;
 	ASSERT(!(*bpp)->b_error);
 
 	agf = XFS_BUF_TO_AGF(*bpp);
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index cfcef076c72f..10b7284cac35 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -3311,13 +3311,14 @@  xfs_bmap_longest_free_extent(
 	pag = xfs_perag_get(mp, ag);
 	if (!pag->pagf_init) {
 		error = xfs_alloc_pagf_init(mp, tp, ag, XFS_ALLOC_FLAG_TRYLOCK);
-		if (error)
-			goto out;
-
-		if (!pag->pagf_init) {
+		if (error == -EAGAIN) {
+			/* Couldn't lock the AGF, so skip this AG. */
 			*notinit = 1;
+			error = 0;
 			goto out;
 		}
+		if (error)
+			goto out;
 	}
 
 	longest = xfs_alloc_longest_free_extent(pag,
diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c
index 5f12b5d8527a..3ccdab463359 100644
--- a/fs/xfs/xfs_filestream.c
+++ b/fs/xfs/xfs_filestream.c
@@ -159,16 +159,17 @@  xfs_filestream_pick_ag(
 
 		if (!pag->pagf_init) {
 			err = xfs_alloc_pagf_init(mp, NULL, ag, trylock);
-			if (err && !trylock) {
+			if (err == -EAGAIN) {
+				/* Couldn't lock the AGF, skip this AG. */
+				xfs_perag_put(pag);
+				continue;
+			}
+			if (err) {
 				xfs_perag_put(pag);
 				return err;
 			}
 		}
 
-		/* Might fail sometimes during the 1st pass with trylock set. */
-		if (!pag->pagf_init)
-			goto next_ag;
-
 		/* Keep track of the AG with the most free blocks. */
 		if (pag->pagf_freeblks > maxfree) {
 			maxfree = pag->pagf_freeblks;