On Aug 18, 2017, at 12:19 PM, Andreas Dilger <adilger@xxxxxxxxx> wrote: > > If there is a directory with more than EXT2_LINK_MAX (65000) > subdirectories, but the DIR_NLINK feature is not set in the > superblock, the feature should be set before continuing on > to change the on-disk directory link count to 1. > > While most filesystems should have DIR_NLINK set (it was set > by default for all ext4 filesystems, and the kernel before > 4.12 automatically set it if the directory link count grew > too large), it is possible that this flag is lost due to disk > corruption or for an upgraded filesystem. We no longer want > the kernel to automatically enable this feature. > > Addresses: https://bugzilla.kernel.org/show_bug.cgi?id=196405 > Signed-off-by: Andreas Dilger <adilger@xxxxxxxxx> > --- Note that this is using the f_large_dir test for verification, since it was already creating a directory with 48k entries in it and already took ages to run because directory processing in libext2fs is O(n^2) (it took about 2h to finish in my VM). The alternative is storing a 100MB image file (though it may be possible to compress it significantly). I'm working on a patch to improve the debugfs "expand" command so that it can insert multiple directory blocks at once, rather than one-at-a-time (after a full directory scan). That at least fixes half of the problem. Cheers, Andreas > e2fsck/pass4.c | 12 +++++++++- > e2fsck/problem.c | 5 ++++ > e2fsck/problem.h | 3 +++ > tests/f_large_dir/expect | 7 ++++-- > tests/f_large_dir/script | 60 ++++++++++++++++++++++++++++++------------------ > 5 files changed, 62 insertions(+), 25 deletions(-) > > diff --git a/e2fsck/pass4.c b/e2fsck/pass4.c > index 663f87a..d0ff8e9 100644 > --- a/e2fsck/pass4.c > +++ b/e2fsck/pass4.c > @@ -170,6 +170,7 @@ void e2fsck_pass4(e2fsck_t ctx) > #endif > struct problem_context pctx; > __u16 link_count, link_counted; > + int dir_nlink_fs; > char *buf = 0; > dgrp_t group, maxgroup; > > @@ -193,6 +194,8 @@ void e2fsck_pass4(e2fsck_t ctx) > if (!(ctx->options & E2F_OPT_PREEN)) > fix_problem(ctx, PR_4_PASS_HEADER, &pctx); > > + dir_nlink_fs = ext2fs_has_feature_dir_nlink(fs->super); > + > group = 0; > maxgroup = fs->group_desc_count; > if (ctx->progress) > @@ -249,8 +252,15 @@ void e2fsck_pass4(e2fsck_t ctx) > &link_counted); > } > isdir = ext2fs_test_inode_bitmap2(ctx->inode_dir_map, i); > - if (isdir && (link_counted > EXT2_LINK_MAX)) > + if (isdir && (link_counted > EXT2_LINK_MAX)) { > + if (!dir_nlink_fs && > + fix_problem(ctx, PR_4_DIR_NLINK_FEATURE, &pctx)) { > + ext2fs_set_feature_dir_nlink(fs->super); > + ext2fs_mark_super_dirty(fs); > + dir_nlink_fs = 1; > + } > link_counted = 1; > + } > if (link_counted != link_count) { > e2fsck_read_inode_full(ctx, i, EXT2_INODE(inode), > inode_size, "pass4"); > diff --git a/e2fsck/problem.c b/e2fsck/problem.c > index 9706933..25c1de9 100644 > --- a/e2fsck/problem.c > +++ b/e2fsck/problem.c > @@ -1873,6 +1873,11 @@ static struct e2fsck_problem problem_table[] = { > N_("@a @i %i ref count is %N, @s %n. "), > PROMPT_FIX, PR_PREEN_OK }, > > + /* directory exceeds max links, but no DIR_NLINK feature in superblock*/ > + { PR_4_DIR_NLINK_FEATURE, > + N_("@d exceeds max links, but no DIR_NLINK feature in @S.\n"), > + PROMPT_FIX, 0 }, > + > /* Pass 5 errors */ > > /* Pass 5: Checking group summary information */ > diff --git a/e2fsck/problem.h b/e2fsck/problem.h > index f30f8f0..07ed0a7 100644 > --- a/e2fsck/problem.h > +++ b/e2fsck/problem.h > @@ -1134,6 +1134,9 @@ struct problem_context { > /* Extended attribute inode ref count wrong */ > #define PR_4_EA_INODE_REF_COUNT 0x040005 > > +/* directory exceeds max links, but no DIR_NLINK feature in superblock */ > +#define PR_4_DIR_NLINK_FEATURE 0x040006 > + > /* > * Pass 5 errors > */ > diff --git a/tests/f_large_dir/expect b/tests/f_large_dir/expect > index b099460..4b9ca6f 100644 > --- a/tests/f_large_dir/expect > +++ b/tests/f_large_dir/expect > @@ -3,10 +3,13 @@ Pass 2: Checking directory structure > Pass 3: Checking directory connectivity > Pass 3A: Optimizing directories > Pass 4: Checking reference counts > -Inode 13 ref count is 1, should be 47245. Fix? yes > +Directory exceeds max links, but no DIR_NLINK feature in superblock. > +Fix? yes > + > +Inode 12 ref count is 65012, should be 1. Fix? yes > > Pass 5: Checking group summary information > > test.img: ***** FILE SYSTEM WAS MODIFIED ***** > -test.img: 13/115368 files (0.0% non-contiguous), 32817/460800 blocks > +test.img: 65023/65104 files (0.0% non-contiguous), 96668/100937 blocks > Exit status is 1 > diff --git a/tests/f_large_dir/script b/tests/f_large_dir/script > index 0b5fdff..a10fe16 100644 > --- a/tests/f_large_dir/script > +++ b/tests/f_large_dir/script > @@ -5,43 +5,59 @@ E2FSCK=../e2fsck/e2fsck > NAMELEN=255 > DIRENT_SZ=8 > BLOCKSZ=1024 > +INODESZ=128 > DIRENT_PER_LEAF=$((BLOCKSZ / (NAMELEN + DIRENT_SZ))) > HEADER=32 > INDEX_SZ=8 > INDEX_L1=$(((BLOCKSZ - HEADER) / INDEX_SZ)) > INDEX_L2=$(((BLOCKSZ - DIRENT_SZ) / INDEX_SZ)) > ENTRIES=$((INDEX_L1 * INDEX_L2 * DIRENT_PER_LEAF)) > +DIRBLK=$((2 + INDEX_L1 * INDEX_L2)) > +EXT4_LINK_MAX=65000 > +[ $ENTRIES -lt $((EXT4_LINK_MAX + 10)) ] && ENTRIES=$((EXT4_LINK_MAX + 10)) > +FSIZE=$(((DIRBLK + EXT4_LINK_MAX * ((BLOCKSZ + INODESZ) / BLOCKSZ)) * 5 / 4)) > > -cp /dev/null $OUT > -$MKE2FS -b 1024 -O large_dir,uninit_bg,dir_nlink -F $TMPFILE 460800 \ > - > /dev/null 2>&1 > +> $OUT > +$MKE2FS -b 1024 -O large_dir,uninit_bg -N $((ENTRIES + 50)) \ > + -I $INODESZ -F $TMPFILE $FSIZE > $OUT 2>&1 > +RC=$? > +if [ $RC -eq 0 ]; then > { > - echo "feature large_dir" > + START=$SECONDS > echo "mkdir /foo" > echo "cd /foo" > - touch foofile > - echo "write foofile foofile" > + touch $TMPFILE.tmp > + echo "write $TMPFILE.tmp foofile" > i=0 > - while test $i -lt $ENTRIES ; do > - if test $(( i % DIRENT_PER_LEAF )) -eq 0 ; then > - echo "expand ./" > + while test $i -lt $ENTRIES ; do > + if test $((i % DIRENT_PER_LEAF)) -eq 0; then > + echo "expand ./" > fi > - if test $(( i % 5000 )) -eq 0 -a $i -gt 0 ; then > - >&2 echo "$test_name: $i processed" > + if test $((i % 5000)) -eq 0 -a $i -gt 0; then > + ELAPSED=$((SECONDS - START)) > + RATE=$((i / ELAPSED)) > + >&2 echo "$test_name: $i processed in ${ELAPSED}s @ $RATE/s" > fi > - printf "ln foofile %0255X\n" $i > - i=$(($i + 1)) > + if test $i -lt $((EXT4_LINK_MAX + 10)); then > + printf "mkdir d%0254u\n" $i > + else > + printf "ln foofile f%0254u\n" $i > + fi > + i=$((i + 1)) > done > -} | $DEBUGFS -w -f /dev/stdin $TMPFILE > /dev/null 2>&1 > - > -$E2FSCK -yfD $TMPFILE > $OUT.new 2>&1 > -status=$? > -echo Exit status is $status >> $OUT.new > -sed -f $cmd_dir/filter.sed -e "s;$TMPFILE;test.img;" $OUT.new >> $OUT > -rm -f $OUT.new > +} | $DEBUGFS -w -f /dev/stdin $TMPFILE > $OUT > + RC=$? > +fi > +if [ $RC -eq 0 ]; then > + $E2FSCK -yfD $TMPFILE > $OUT.new 2>&1 > + status=$? > + echo "Exit status is $status" >> $OUT.new > + sed -f $cmd_dir/filter.sed -e "s;$TMPFILE;test.img;" $OUT.new > $OUT > + rm -f $OUT.new > > -cmp -s $OUT $EXP > -RC=$? > + cmp -s $OUT $EXP > + RC=$? > +fi > if [ $RC -eq 0 ]; then > echo "$test_name: $test_description: ok" > touch $test_name.ok > -- > 1.8.0 > Cheers, Andreas
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