diff options
Diffstat (limited to 'sys/ufs')
| -rw-r--r-- | sys/ufs/ffs/ffs_alloc.c | 29 |
1 files changed, 15 insertions, 14 deletions
diff --git a/sys/ufs/ffs/ffs_alloc.c b/sys/ufs/ffs/ffs_alloc.c index cb0bfeda58a..249ac385938 100644 --- a/sys/ufs/ffs/ffs_alloc.c +++ b/sys/ufs/ffs/ffs_alloc.c @@ -1,4 +1,4 @@ -/* $OpenBSD: ffs_alloc.c,v 1.111 2020/05/28 15:48:29 otto Exp $ */ +/* $OpenBSD: ffs_alloc.c,v 1.112 2020/05/29 06:46:15 otto Exp $ */ /* $NetBSD: ffs_alloc.c,v 1.11 1996/05/11 18:27:09 mycroft Exp $ */ /* @@ -515,7 +515,7 @@ ffs_dirpref(struct inode *pip) maxcontigdirs = 1; /* - * Limit number of dirs in one cg and reserve space for + * Limit number of dirs in one cg and reserve space for * regular files, but only if we have no deficit in * inodes or space. * @@ -524,16 +524,17 @@ ffs_dirpref(struct inode *pip) * We scan from our preferred cylinder group forward looking * for a cylinder group that meets our criterion. If we get * to the final cylinder group and do not find anything, - * we start scanning backwards from our preferred cylinder - * group. The ideal would be to alternate looking forward - * and backward, but tha tis just too complex to code for - * the gain it would get. The most likely place where the - * backward scan would take effect is when we start near - * the end of the filesystem and do not find anything from - * where we are to the end. In that case, scanning backward - * will likely find us a suitable cylinder group much closer - * to our desired location than if we were to start scanning - * forward from the beginning for the filesystem. + * we start scanning forwards from the beginning of the + * filesystem. While it might seem sensible to start scanning + * backwards or even to alternate looking forward and backward, + * this approach fails badly when the filesystem is nearly full. + * Specifically, we first search all the areas that have no space + * and finally try the one preceding that. We repeat this on + * every request and in the case of the final block end up + * searching the entire filesystem. By jumping to the front + * of the filesystem, our future forward searches always look + * in new cylinder groups so finds every possible block after + * one pass over the filesystem. */ for (cg = prefcg; cg < fs->fs_ncg; cg++) if (fs->fs_cs(fs, cg).cs_ndir < maxndir && @@ -542,7 +543,7 @@ ffs_dirpref(struct inode *pip) if (fs->fs_contigdirs[cg] < maxcontigdirs) goto end; } - for (cg = prefcg - 1; cg >= 0; cg--) + for (cg = 0; cg < prefcg; cg++) if (fs->fs_cs(fs, cg).cs_ndir < maxndir && fs->fs_cs(fs, cg).cs_nifree >= minifree && fs->fs_cs(fs, cg).cs_nbfree >= minbfree) { @@ -555,7 +556,7 @@ ffs_dirpref(struct inode *pip) for (cg = prefcg; cg < fs->fs_ncg; cg++) if (fs->fs_cs(fs, cg).cs_nifree >= avgifree) goto end; - for (cg = prefcg - 1; cg >= 0; cg--) + for (cg = 0; cg < prefcg; cg++) if (fs->fs_cs(fs, cg).cs_nifree >= avgifree) goto end; end: |