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Date: Tue, 21 Jul 2020 12:36:59 +0200 From: Lukas Czerner <lczerner@...hat.com> To: Jan Kara <jack@...e.cz> Cc: Ted Tso <tytso@....edu>, linux-ext4@...r.kernel.org, Ritesh Harjani <riteshh@...ux.ibm.com>, Wolfgang Frisch <wolfgang.frisch@...e.com> Subject: Re: [PATCH 2/4] ext4: Don't allow overlapping system zones On Wed, Jul 15, 2020 at 03:18:10PM +0200, Jan Kara wrote: > Currently, add_system_zone() just silently merges two added system zones > that overlap. However the overlap should not happen and it generally > suggests that some unrelated metadata overlap which indicates the fs is > corrupted. We should have caught such problems earlier (e.g. in > ext4_check_descriptors()) but add this check as another line of defense. > In later patch we also use this for stricter checking of journal inode > extent tree. Looks good, thanks! Reviewed-by: Lukas Czerner <lczerner@...hat.com> > > Signed-off-by: Jan Kara <jack@...e.cz> > --- > fs/ext4/block_validity.c | 36 +++++++++++++----------------------- > 1 file changed, 13 insertions(+), 23 deletions(-) > > diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c > index 16e9b2fda03a..b394a50ebbe3 100644 > --- a/fs/ext4/block_validity.c > +++ b/fs/ext4/block_validity.c > @@ -68,7 +68,7 @@ static int add_system_zone(struct ext4_system_blocks *system_blks, > ext4_fsblk_t start_blk, > unsigned int count) > { > - struct ext4_system_zone *new_entry = NULL, *entry; > + struct ext4_system_zone *new_entry, *entry; > struct rb_node **n = &system_blks->root.rb_node, *node; > struct rb_node *parent = NULL, *new_node = NULL; > > @@ -79,30 +79,20 @@ static int add_system_zone(struct ext4_system_blocks *system_blks, > n = &(*n)->rb_left; > else if (start_blk >= (entry->start_blk + entry->count)) > n = &(*n)->rb_right; > - else { > - if (start_blk + count > (entry->start_blk + > - entry->count)) > - entry->count = (start_blk + count - > - entry->start_blk); > - new_node = *n; > - new_entry = rb_entry(new_node, struct ext4_system_zone, > - node); > - break; > - } > + else /* Unexpected overlap of system zones. */ > + return -EFSCORRUPTED; > } > > - if (!new_entry) { > - new_entry = kmem_cache_alloc(ext4_system_zone_cachep, > - GFP_KERNEL); > - if (!new_entry) > - return -ENOMEM; > - new_entry->start_blk = start_blk; > - new_entry->count = count; > - new_node = &new_entry->node; > - > - rb_link_node(new_node, parent, n); > - rb_insert_color(new_node, &system_blks->root); > - } > + new_entry = kmem_cache_alloc(ext4_system_zone_cachep, > + GFP_KERNEL); > + if (!new_entry) > + return -ENOMEM; > + new_entry->start_blk = start_blk; > + new_entry->count = count; > + new_node = &new_entry->node; > + > + rb_link_node(new_node, parent, n); > + rb_insert_color(new_node, &system_blks->root); > > /* Can we merge to the left? */ > node = rb_prev(new_node); > -- > 2.16.4 >
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