| Message ID | 20220423014216.34032-1-artem.blagodarenko@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [RFC] LUS-10810 e2fsck: use bitmaps for in-use block map | expand |
On Apr 22, 2022, at 7:42 PM, Artem Blagodarenko <artem.blagodarenko@gmail.com> wrote: > > From: Artem Blagodarenko <artem.blagodarenko@hpe.com> > > EXT2FS_BMAP64_RBTREE is too expensive for fragmented prtition, > that can lead to situation than e2fsck use swapfile. > > This patch change EXT2FS_BMAP64_RBTREE to bitmap. > > Marked as RFC because it must be descussed whether this flags > should be changed by default or some additional option or > a heuristic is needed to contol this flags. Artem, I think switching over to a bitmap would be worse for the case of relatively empty filesystems, and would likely increase memory usage for many full filesystems as well. For a very large filesystem a full bitmap might take tens of GB of RAM per use. I think a better (but more complex) solution would be to have a hybrid model, where an rbtree is used for a group if it is more efficient, but once there are too many fragments in a group and it consumes as much memory than a bitmap (4KB) then it would be flattened into a rbtree leaf that is a 4KB bitmap so it doesn't keep expanding. That would give the best of both worlds, but I have no idea how easy/hard this would be to implement. Cheers, Andreas > signed-off-by: Artem Blagodarenko <artem.blagodarenko@hpe.com> > > Change-Id: I6a906b5e54cf40eaba82624d8e4c2b0f90132813 > --- > e2fsck/pass1.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c > index 26b9ab71..563dcdc5 100644 > --- a/e2fsck/pass1.c > +++ b/e2fsck/pass1.c > @@ -1247,7 +1247,7 @@ void e2fsck_pass1(e2fsck_t ctx) > return; > } > pctx.errcode = e2fsck_allocate_subcluster_bitmap(fs, > - _("in-use block map"), EXT2FS_BMAP64_RBTREE, > + _("in-use block map"), EXT2FS_BMAP64_BITARRAY, > "block_found_map", &ctx->block_found_map); > if (pctx.errcode) { > pctx.num = 1; > @@ -1256,7 +1256,7 @@ void e2fsck_pass1(e2fsck_t ctx) > return; > } > pctx.errcode = e2fsck_allocate_block_bitmap(fs, > - _("metadata block map"), EXT2FS_BMAP64_RBTREE, > + _("metadata block map"), EXT2FS_BMAP64_BITARRAY, > "block_metadata_map", &ctx->block_metadata_map); > if (pctx.errcode) { > pctx.num = 1; > @@ -2456,7 +2456,7 @@ static int check_ext_attr(e2fsck_t ctx, struct problem_context *pctx, > if (!ctx->block_ea_map) { > pctx->errcode = e2fsck_allocate_block_bitmap(fs, > _("ext attr block map"), > - EXT2FS_BMAP64_RBTREE, "block_ea_map", > + EXT2FS_BMAP64_BITARRAY, "block_ea_map", > &ctx->block_ea_map); > if (pctx->errcode) { > pctx->num = 2; > -- > 2.27.0 > Cheers, Andreas
diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c index 26b9ab71..563dcdc5 100644 --- a/e2fsck/pass1.c +++ b/e2fsck/pass1.c @@ -1247,7 +1247,7 @@ void e2fsck_pass1(e2fsck_t ctx) return; } pctx.errcode = e2fsck_allocate_subcluster_bitmap(fs, - _("in-use block map"), EXT2FS_BMAP64_RBTREE, + _("in-use block map"), EXT2FS_BMAP64_BITARRAY, "block_found_map", &ctx->block_found_map); if (pctx.errcode) { pctx.num = 1; @@ -1256,7 +1256,7 @@ void e2fsck_pass1(e2fsck_t ctx) return; } pctx.errcode = e2fsck_allocate_block_bitmap(fs, - _("metadata block map"), EXT2FS_BMAP64_RBTREE, + _("metadata block map"), EXT2FS_BMAP64_BITARRAY, "block_metadata_map", &ctx->block_metadata_map); if (pctx.errcode) { pctx.num = 1; @@ -2456,7 +2456,7 @@ static int check_ext_attr(e2fsck_t ctx, struct problem_context *pctx, if (!ctx->block_ea_map) { pctx->errcode = e2fsck_allocate_block_bitmap(fs, _("ext attr block map"), - EXT2FS_BMAP64_RBTREE, "block_ea_map", + EXT2FS_BMAP64_BITARRAY, "block_ea_map", &ctx->block_ea_map); if (pctx->errcode) { pctx->num = 2;