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Message-ID: <20240103113131.z4jhwim7bzynhrlx@quack3> Date: Wed, 3 Jan 2024 12:31:31 +0100 From: Jan Kara <jack@...e.cz> To: Zhang Yi <yi.zhang@...weicloud.com> Cc: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz, ritesh.list@...il.com, hch@...radead.org, djwong@...nel.org, willy@...radead.org, yi.zhang@...wei.com, chengzhihao1@...wei.com, yukuai3@...wei.com, wangkefeng.wang@...wei.com Subject: Re: [RFC PATCH v2 05/25] ext4: make ext4_map_blocks() distinguish delalloc only extent On Tue 02-01-24 20:38:58, Zhang Yi wrote: > From: Zhang Yi <yi.zhang@...wei.com> > > Add a new map flag EXT4_MAP_DELAYED to indicate the mapping range is a > delayed allocated only (not unwritten) one, and making > ext4_map_blocks() can distinguish it, no longer mixing it with holes. > > Signed-off-by: Zhang Yi <yi.zhang@...wei.com> One small comment below. > --- > fs/ext4/ext4.h | 4 +++- > fs/ext4/extents.c | 5 +++-- > fs/ext4/inode.c | 2 ++ > 3 files changed, 8 insertions(+), 3 deletions(-) > > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h > index a5d784872303..55195909d32f 100644 > --- a/fs/ext4/ext4.h > +++ b/fs/ext4/ext4.h > @@ -252,8 +252,10 @@ struct ext4_allocation_request { > #define EXT4_MAP_MAPPED BIT(BH_Mapped) > #define EXT4_MAP_UNWRITTEN BIT(BH_Unwritten) > #define EXT4_MAP_BOUNDARY BIT(BH_Boundary) > +#define EXT4_MAP_DELAYED BIT(BH_Delay) > #define EXT4_MAP_FLAGS (EXT4_MAP_NEW | EXT4_MAP_MAPPED |\ > - EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY) > + EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY |\ > + EXT4_MAP_DELAYED) > > struct ext4_map_blocks { > ext4_fsblk_t m_pblk; > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > index 0892d0568013..fc69f13cf510 100644 > --- a/fs/ext4/extents.c > +++ b/fs/ext4/extents.c > @@ -4073,9 +4073,10 @@ static void ext4_ext_determine_hole(struct inode *inode, > } else if (in_range(map->m_lblk, es.es_lblk, es.es_len)) { > /* > * Straddle the beginning of the queried range, it's no > - * longer a hole, adjust the length to the delayed extent's > - * after map->m_lblk. > + * longer a hole, mark it is a delalloc and adjust the > + * length to the delayed extent's after map->m_lblk. > */ > + map->m_flags |= EXT4_MAP_DELAYED; I wouldn't set delalloc bit here. If there's delalloc extent containing lblk now, it means the caller of ext4_map_blocks() is not holding i_rwsem (otherwise we would have found already in ext4_map_blocks()) and thus delalloc info is unreliable anyway. So I wouldn't bother. But it's worth a comment here like: /* * There's delalloc extent containing lblk. It must have * been added after ext4_map_blocks() checked the extent * status tree so we are not holding i_rwsem and delalloc * info is only stabilized by i_data_sem we are going to * release soon. Don't modify the extent status tree and * report extent as a hole. */ Honza > len = es.es_lblk + es.es_len - map->m_lblk; > goto out; > } else { > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 1b5e6409f958..c141bf6d8db2 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -515,6 +515,8 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode, > map->m_len = retval; > } else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) { > map->m_pblk = 0; > + map->m_flags |= ext4_es_is_delayed(&es) ? > + EXT4_MAP_DELAYED : 0; > retval = es.es_len - (map->m_lblk - es.es_lblk); > if (retval > map->m_len) > retval = map->m_len; > -- > 2.39.2 > -- Jan Kara <jack@...e.com> SUSE Labs, CR
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