From c3ce5aa9b02dd912e381237e7f98d591d7358cdc Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Fri, 8 Dec 2017 21:11:39 +0100 Subject: [PATCH] gfs2: Fix metadata read-ahead during truncate The metadata read-ahead algorithm broke when switching from recursive to non-recursive delete: the current algorithm reads ahead blocks at height N - 1 while deallocating the blocks at hight N. However, deallocating the blocks at height N requires a complete walk of the metadata tree, not only down to height N - 1. Consequently, all blocks below height N - 1 will be accessed without read-ahead. Fix this by issuing read-aheads as early as possible, after each metapath lookup. Signed-off-by: Andreas Gruenbacher Signed-off-by: Bob Peterson --- fs/gfs2/bmap.c | 42 +++++++++++++++++++++++++----------------- 1 file changed, 25 insertions(+), 17 deletions(-) diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c index 1110aa9f6f31..e983b5872679 100644 --- a/fs/gfs2/bmap.c +++ b/fs/gfs2/bmap.c @@ -279,14 +279,17 @@ static inline __be64 *metapointer(unsigned int height, const struct metapath *mp return p + mp->mp_list[height]; } -static void gfs2_metapath_ra(struct gfs2_glock *gl, - const struct buffer_head *bh, const __be64 *pos) +static void gfs2_metapath_ra(struct gfs2_glock *gl, struct metapath *mp, + unsigned int height) { - struct buffer_head *rabh; + struct buffer_head *bh = mp->mp_bh[height]; + const __be64 *pos = metapointer(height, mp); const __be64 *endp = (const __be64 *)(bh->b_data + bh->b_size); const __be64 *t; for (t = pos; t < endp; t++) { + struct buffer_head *rabh; + if (!*t) continue; @@ -353,12 +356,13 @@ static int lookup_metapath(struct gfs2_inode *ip, struct metapath *mp) * * Similar to lookup_metapath, but does lookups for a range of heights * - * Returns: error + * Returns: error or the number of buffers filled */ static int fillup_metapath(struct gfs2_inode *ip, struct metapath *mp, int h) { unsigned int x = 0; + int ret; if (h) { /* find the first buffer we need to look up. */ @@ -367,7 +371,10 @@ static int fillup_metapath(struct gfs2_inode *ip, struct metapath *mp, int h) break; } } - return __fillup_metapath(ip, mp, x, h); + ret = __fillup_metapath(ip, mp, x, h); + if (ret) + return ret; + return mp->mp_aheight - x - 1; } static inline void release_metapath(struct metapath *mp) @@ -1309,7 +1316,6 @@ static int trunc_dealloc(struct gfs2_inode *ip, u64 newsize) u32 btotal = 0; int ret, state; int mp_h; /* metapath buffers are read in to this height */ - sector_t last_ra = 0; u64 prev_bnr = 0; bool preserve1; /* need to preserve the first meta pointer? */ @@ -1331,6 +1337,11 @@ static int trunc_dealloc(struct gfs2_inode *ip, u64 newsize) ret = lookup_metapath(ip, &mp); if (ret) goto out_metapath; + + /* issue read-ahead on metadata */ + for (mp_h = 0; mp_h < mp.mp_aheight - 1; mp_h++) + gfs2_metapath_ra(ip->i_gl, &mp, mp_h); + if (mp.mp_aheight == ip->i_height) state = DEALLOC_MP_FULL; /* We have a complete metapath */ else @@ -1352,16 +1363,6 @@ static int trunc_dealloc(struct gfs2_inode *ip, u64 newsize) /* Truncate a full metapath at the given strip height. * Note that strip_h == mp_h in order to be in this state. */ case DEALLOC_MP_FULL: - if (mp_h > 0) { /* issue read-ahead on metadata */ - __be64 *top; - - bh = mp.mp_bh[mp_h - 1]; - if (bh->b_blocknr != last_ra) { - last_ra = bh->b_blocknr; - top = metaptr1(mp_h - 1, &mp); - gfs2_metapath_ra(ip->i_gl, bh, top); - } - } /* If we're truncating to a non-zero size and the mp is at the beginning of file for the strip height, we need to preserve the first metadata pointer. */ @@ -1427,9 +1428,16 @@ static int trunc_dealloc(struct gfs2_inode *ip, u64 newsize) case DEALLOC_FILL_MP: /* Fill the buffers out to the current height. */ ret = fillup_metapath(ip, &mp, mp_h); - if (ret) + if (ret < 0) goto out; + /* issue read-ahead on metadata */ + if (mp.mp_aheight > 1) { + for (; ret > 1; ret--) + gfs2_metapath_ra(ip->i_gl, &mp, + mp.mp_aheight - ret); + } + /* If buffers found for the entire strip height */ if (mp.mp_aheight - 1 == strip_h) { state = DEALLOC_MP_FULL; -- 2.11.0