On 2020/5/22 3:13, [email protected] wrote: > From: Ira Weiny<[email protected]> > > We add 'always', 'never', and 'inode' (default). '-o dax' continues to > operate the same which is equivalent to 'always'. This new > functionality is limited to ext4 only. > > Specifically we introduce a 2nd DAX mount flag EXT4_MOUNT2_DAX_NEVER and set > it and EXT4_MOUNT_DAX_ALWAYS appropriately for the mode. > > We also force EXT4_MOUNT2_DAX_NEVER if !CONFIG_FS_DAX. > > Finally, EXT4_MOUNT2_DAX_INODE is used solely to detect if the user > specified that option for printing. Hi Ira,
I have two questions when reviewing this patch: 1) After doing mount with the same dax=inode option, ext4/xfs shows differnt output(i.e. xfs doesn't print 'dax=inode'): --------------------------------------------------- # mount -o dax=inode /dev/pmem0 /mnt/xfstests/test/ # mount | grep pmem0 /dev/pmem0 on /mnt/xfstests/test type ext4 (rw,relatime,seclabel,dax=inode) # mount -odax=inode /dev/pmem1 /mnt/xfstests/scratch/ # mount | grep pmem1 /dev/pmem1 on /mnt/xfstests/scratch type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota) ---------------------------------------------------- Is this expected output? why don't unify the output? 2) Do mount without dax and mount with -odax=inode have the same behavior? --------------------------------------------------- # mount /dev/pmem0 /mnt/xfstests/test/ # mount | grep pmem0 /dev/pmem0 on /mnt/xfstests/test type ext4 (rw,relatime,seclabel) # umount /mnt/xfstests/test # mount -odax=inode /dev/pmem0 /mnt/xfstests/test/ # mount | grep pmem0 /dev/pmem0 on /mnt/xfstests/test type ext4 (rw,relatime,seclabel,dax=inode --------------------------------------------------- BTW: I focus on the support of per-file/directory DAX operations recently. > > Reviewed-by: Jan Kara<[email protected]> > Signed-off-by: Ira Weiny<[email protected]> > > --- > Changes from V1: > Fix up mounting options to only show an option if specified > Fix remount to prevent dax changes > Isolate behavior to ext4 only > > Changes from RFC: > Combine remount check for DAX_NEVER with DAX_ALWAYS > Update ext4_should_enable_dax() > --- > fs/ext4/ext4.h | 2 ++ > fs/ext4/inode.c | 2 ++ > fs/ext4/super.c | 67 +++++++++++++++++++++++++++++++++++++++++-------- > 3 files changed, 61 insertions(+), 10 deletions(-) > > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h > index f5291693ce6e..65ffb831b2b9 100644 > --- a/fs/ext4/ext4.h > +++ b/fs/ext4/ext4.h > @@ -1168,6 +1168,8 @@ struct ext4_inode_info { > blocks */ > #define EXT4_MOUNT2_HURD_COMPAT 0x00000004 /* Support > HURD-castrated > file systems */ > +#define EXT4_MOUNT2_DAX_NEVER 0x00000008 /* Do not allow > Direct Access */ > +#define EXT4_MOUNT2_DAX_INODE 0x00000010 /* For printing > options only */ > > #define EXT4_MOUNT2_EXPLICIT_JOURNAL_CHECKSUM 0x00000008 /* User > explicitly > specified journal checksum */ > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 01636cf5f322..68fac9289109 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -4402,6 +4402,8 @@ static bool ext4_should_enable_dax(struct inode *inode) > { > struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); > > + if (test_opt2(inode->i_sb, DAX_NEVER)) > + return false; > if (!S_ISREG(inode->i_mode)) > return false; > if (ext4_should_journal_data(inode)) > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index 80eb814c47eb..5e056aa20ce9 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -1512,7 +1512,8 @@ enum { > Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota, > Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_jqfmt_vfsv1, Opt_quota, > Opt_noquota, Opt_barrier, Opt_nobarrier, Opt_err, > - Opt_usrquota, Opt_grpquota, Opt_prjquota, Opt_i_version, Opt_dax, > + Opt_usrquota, Opt_grpquota, Opt_prjquota, Opt_i_version, > + Opt_dax, Opt_dax_always, Opt_dax_inode, Opt_dax_never, > Opt_stripe, Opt_delalloc, Opt_nodelalloc, Opt_warn_on_error, > Opt_nowarn_on_error, Opt_mblk_io_submit, > Opt_lazytime, Opt_nolazytime, Opt_debug_want_extra_isize, > @@ -1579,6 +1580,9 @@ static const match_table_t tokens = { > {Opt_nobarrier, "nobarrier"}, > {Opt_i_version, "i_version"}, > {Opt_dax, "dax"}, > + {Opt_dax_always, "dax=always"}, > + {Opt_dax_inode, "dax=inode"}, > + {Opt_dax_never, "dax=never"}, > {Opt_stripe, "stripe=%u"}, > {Opt_delalloc, "delalloc"}, > {Opt_warn_on_error, "warn_on_error"}, > @@ -1726,6 +1730,7 @@ static int clear_qf_name(struct super_block *sb, int > qtype) > #define MOPT_NO_EXT3 0x0200 > #define MOPT_EXT4_ONLY (MOPT_NO_EXT2 | MOPT_NO_EXT3) > #define MOPT_STRING 0x0400 > +#define MOPT_SKIP 0x0800 > > static const struct mount_opts { > int token; > @@ -1775,7 +1780,13 @@ static const struct mount_opts { > {Opt_min_batch_time, 0, MOPT_GTE0}, > {Opt_inode_readahead_blks, 0, MOPT_GTE0}, > {Opt_init_itable, 0, MOPT_GTE0}, > - {Opt_dax, EXT4_MOUNT_DAX_ALWAYS, MOPT_SET}, > + {Opt_dax, EXT4_MOUNT_DAX_ALWAYS, MOPT_SET | MOPT_SKIP}, > + {Opt_dax_always, EXT4_MOUNT_DAX_ALWAYS, > + MOPT_EXT4_ONLY | MOPT_SET | MOPT_SKIP}, > + {Opt_dax_inode, EXT4_MOUNT2_DAX_INODE, > + MOPT_EXT4_ONLY | MOPT_SET | MOPT_SKIP}, > + {Opt_dax_never, EXT4_MOUNT2_DAX_NEVER, > + MOPT_EXT4_ONLY | MOPT_SET | MOPT_SKIP}, > {Opt_stripe, 0, MOPT_GTE0}, > {Opt_resuid, 0, MOPT_GTE0}, > {Opt_resgid, 0, MOPT_GTE0}, > @@ -2084,13 +2095,32 @@ static int handle_mount_opt(struct super_block *sb, > char *opt, int token, > } > sbi->s_jquota_fmt = m->mount_opt; > #endif > - } else if (token == Opt_dax) { > + } else if (token == Opt_dax || token == Opt_dax_always || > + token == Opt_dax_inode || token == Opt_dax_never) { > #ifdef CONFIG_FS_DAX > - ext4_msg(sb, KERN_WARNING, > - "DAX enabled. Warning: EXPERIMENTAL, use at your own risk"); > - sbi->s_mount_opt |= m->mount_opt; > + switch (token) { > + case Opt_dax: > + case Opt_dax_always: > + ext4_msg(sb, KERN_WARNING, > + "DAX enabled. Warning: EXPERIMENTAL, use at > your own risk"); > + sbi->s_mount_opt |= EXT4_MOUNT_DAX_ALWAYS; > + sbi->s_mount_opt2&= ~EXT4_MOUNT2_DAX_NEVER; > + break; > + case Opt_dax_never: > + sbi->s_mount_opt2 |= EXT4_MOUNT2_DAX_NEVER; > + sbi->s_mount_opt&= ~EXT4_MOUNT_DAX_ALWAYS; > + break; > + case Opt_dax_inode: > + sbi->s_mount_opt&= ~EXT4_MOUNT_DAX_ALWAYS; > + sbi->s_mount_opt2&= ~EXT4_MOUNT2_DAX_NEVER; > + /* Strictly for printing options */ > + sbi->s_mount_opt2 |= EXT4_MOUNT2_DAX_INODE; > + break; > + } > #else > ext4_msg(sb, KERN_INFO, "dax option not supported"); > + sbi->s_mount_opt2 |= EXT4_MOUNT2_DAX_NEVER; > + sbi->s_mount_opt&= ~EXT4_MOUNT_DAX_ALWAYS; > return -1; > #endif For s_mount_opt/s_mount_opt2, could we make the code more readable by using set_opt()/set_opt2()/clear_opt()/clear_opt2() macros? Thanks, Xiao Yang > } else if (token == Opt_data_err_abort) { > @@ -2254,7 +2284,7 @@ static int _ext4_show_options(struct seq_file *seq, > struct super_block *sb, > for (m = ext4_mount_opts; m->token != Opt_err; m++) { > int want_set = m->flags& MOPT_SET; > if (((m->flags& (MOPT_SET|MOPT_CLEAR)) == 0) || > - (m->flags& MOPT_CLEAR_ERR)) > + (m->flags& MOPT_CLEAR_ERR) || m->flags& MOPT_SKIP) > continue; > if (!nodefs&& !(m->mount_opt& (sbi->s_mount_opt ^ > def_mount_opt))) > continue; /* skip if same as the default */ > @@ -2314,6 +2344,17 @@ static int _ext4_show_options(struct seq_file *seq, > struct super_block *sb, > if (DUMMY_ENCRYPTION_ENABLED(sbi)) > SEQ_OPTS_PUTS("test_dummy_encryption"); > > + if (test_opt(sb, DAX_ALWAYS)) { > + if (IS_EXT2_SB(sb)) > + SEQ_OPTS_PUTS("dax"); > + else > + SEQ_OPTS_PUTS("dax=always"); > + } else if (test_opt2(sb, DAX_NEVER)) { > + SEQ_OPTS_PUTS("dax=never"); > + } else if (test_opt2(sb, DAX_INODE)) { > + SEQ_OPTS_PUTS("dax=inode"); > + } > + > ext4_show_quota_options(seq, sb); > return 0; > } > @@ -5436,10 +5477,16 @@ static int ext4_remount(struct super_block *sb, int > *flags, char *data) > goto restore_opts; > } > > - if ((sbi->s_mount_opt ^ old_opts.s_mount_opt)& EXT4_MOUNT_DAX_ALWAYS) { > + if ((sbi->s_mount_opt ^ old_opts.s_mount_opt)& EXT4_MOUNT_DAX_ALWAYS || > + (sbi->s_mount_opt2 ^ old_opts.s_mount_opt2)& EXT4_MOUNT2_DAX_NEVER > || > + (sbi->s_mount_opt2 ^ old_opts.s_mount_opt2)& > EXT4_MOUNT2_DAX_INODE) { > ext4_msg(sb, KERN_WARNING, "warning: refusing change of " > - "dax flag with busy inodes while remounting"); > - sbi->s_mount_opt ^= EXT4_MOUNT_DAX_ALWAYS; > + "dax mount option with busy inodes while remounting"); > + sbi->s_mount_opt&= ~EXT4_MOUNT_DAX_ALWAYS; > + sbi->s_mount_opt |= old_opts.s_mount_opt& > EXT4_MOUNT_DAX_ALWAYS; > + sbi->s_mount_opt2&= ~(EXT4_MOUNT2_DAX_NEVER | > EXT4_MOUNT2_DAX_INODE); > + sbi->s_mount_opt2 |= old_opts.s_mount_opt2& > + (EXT4_MOUNT2_DAX_NEVER | > EXT4_MOUNT2_DAX_INODE); > } > > if (sbi->s_mount_flags& EXT4_MF_FS_ABORTED)
