From: Dan Williams Subject: Re: [PATCH 2/2] ext4, dax: set ext4_dax_aops for dax files Date: Tue, 11 Sep 2018 11:15:18 -0700 Message-ID: References: <20180911154246.6844-1-toshi.kani@hpe.com> <20180911154246.6844-3-toshi.kani@hpe.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Theodore Ts'o , linux-nvdimm , Linux Kernel Mailing List , Andreas Dilger , Jan Kara , linux-ext4 To: Toshi Kani Return-path: In-Reply-To: <20180911154246.6844-3-toshi.kani-ZPxbGqLxI0U@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: linux-ext4.vger.kernel.org On Tue, Sep 11, 2018 at 8:42 AM, Toshi Kani wrote: > Sync syscall to an existing DAX file needs to flush processor cache, > but it does not currently. This is because 'ext4_da_aops' is set to > address_space_operations of existing DAX files, instead of 'ext4_dax_aops', > since S_DAX flag is set after ext4_set_aops() in the open path. > > New file > -------- > lookup_open > ext4_create > __ext4_new_inode > ext4_set_inode_flags // Set S_DAX flag > ext4_set_aops // Set aops to ext4_dax_aops > > Existing file > ------------- > lookup_open > ext4_lookup > ext4_iget > ext4_set_aops // Set aops to ext4_da_aops > ext4_set_inode_flags // Set S_DAX flag > > Change ext4_iget() to call ext4_set_inode_flags() before ext4_set_aops(). > > Fixes: 5f0663bb4a64f588f0a2dd6d1be68d40f9af0086 Same format nit: Fixes: 5f0663bb4a64 ("ext4, dax: introduce ext4_dax_aops") Cc: > Signed-off-by: Toshi Kani > Cc: Jan Kara > Cc: Dan Williams > Cc: "Theodore Ts'o" > Cc: Andreas Dilger > --- > fs/ext4/inode.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 775cd9b4af55..93cbbb859c40 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -4998,6 +4998,8 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) > if (ret) > goto bad_inode; > > + ext4_set_inode_flags(inode); > + Hmm, does this have unintended behavior changes? I notice that there are some checks for flags "IS_APPEND(inode) || IS_IMMUTABLE(inode)" *before* the call to ext4_set_inode_flags(). I didn't look too much deeper at whether those checks are bogus, but it would seem safer to do something like this for a lower risk fix. Thoughts? diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d0dd585add6a..1e9ab445c777 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4999,7 +4999,6 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) if (S_ISREG(inode->i_mode)) { inode->i_op = &ext4_file_inode_operations; inode->i_fop = &ext4_file_operations; - ext4_set_aops(inode); } else if (S_ISDIR(inode->i_mode)) { inode->i_op = &ext4_dir_inode_operations; inode->i_fop = &ext4_dir_operations; @@ -5042,6 +5041,12 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) } brelse(iloc.bh); ext4_set_inode_flags(inode); + /* + * Now that we have determined whether DAX is enabled, set the + * proper address spaces operations + */ + if (S_ISREG(inode->i_mode)) + ext4_set_aops(inode); unlock_new_inode(inode); return inode;