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Message-ID: <20230216130715.kcvcvitdinpv7wwt@quack3> Date: Thu, 16 Feb 2023 14:07:15 +0100 From: Jan Kara <jack@...e.cz> To: zhanchengbin <zhanchengbin1@...wei.com> Cc: Jan Kara <jack@...e.cz>, tytso@....edu, jack@...e.com, linux-ext4@...r.kernel.org, yi.zhang@...wei.com, linfeilong@...wei.com, liuzhiqiang26@...wei.com Subject: Re: [PATCH v4 1/2] ext4: fix inode tree inconsistency caused by ENOMEM in ext4_split_extent_at On Wed 15-02-23 16:51:23, zhanchengbin wrote: > > On 2023/2/14 19:48, Jan Kara wrote: > > On Mon 13-02-23 12:05:21, zhanchengbin wrote: > > > If ENOMEM fails when the extent is splitting, we need to restore the length > > > of the split extent. > > > In the call stack of the ext4_split_extent_at function, only in > > > ext4_ext_create_new_leaf will it alloc memory and change the shape of the > > > extent tree,even if an ENOMEM is returned at this time, the extent tree is > > > still self-consistent, Just restore the split extent lens in the function > > > ext4_split_extent_at. > > > > > > ext4_split_extent_at > > > ext4_ext_insert_extent > > > ext4_ext_create_new_leaf > > > 1)ext4_ext_split > > > ext4_find_extent > > > 2)ext4_ext_grow_indepth > > > ext4_find_extent > > > > > > Signed-off-by: zhanchengbin <zhanchengbin1@...wei.com> > > > --- > > > fs/ext4/extents.c | 3 ++- > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > > > index 9de1c9d1a13d..0f95e857089e 100644 > > > --- a/fs/ext4/extents.c > > > +++ b/fs/ext4/extents.c > > > @@ -935,6 +935,7 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block, > > > bh = read_extent_tree_block(inode, path[ppos].p_idx, --i, flags); > > > if (IS_ERR(bh)) { > > > + EXT4_ERROR_INODE(inode, "IO error reading extent block"); > > > > Why have you added this? Usually we don't log any additional errors for IO > > errors because the storage layer already reports it... Furthermore this > > would potentialy panic the system / remount the fs RO which we also usually > > don't do in case of IO errors, only in case of FS corruption. > > > > Honza > > Because failure of read_extent_tree_block indirectly leads to filesystem > inconsistency in ext4_split_extent_at, I want the filesystem to become > read-only after failure. Can you please describe how exactly? Because I'd rather declare the error directly in ext4_split_extent_at() than in ext4_find_extent() unless it gets too complicated... Honza -- Jan Kara <jack@...e.com> SUSE Labs, CR
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