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Date: Wed, 20 Nov 2019 14:11:07 +0100
From: Jan Kara <jack@...e.cz>
To: Ritesh Harjani <riteshh@...ux.ibm.com>
Cc: jack@...e.cz, tytso@....edu, linux-ext4@...r.kernel.org,
linux-fsdevel@...r.kernel.org, mbobrowski@...browski.org
Subject: Re: [RFCv3 2/4] ext4: Add ext4_ilock & ext4_iunlock API
On Wed 20-11-19 10:30:22, Ritesh Harjani wrote:
> This adds ext4_ilock/iunlock types of APIs.
> This is the preparation APIs to make shared
> locking/unlocking & restarting with exclusive
> locking/unlocking easier in next patch.
>
> Signed-off-by: Ritesh Harjani <riteshh@...ux.ibm.com>
I know XFS does it this way but I don't think we need the obsurity of
additional locking helpers etc. just because of one place in
ext4_dio_write_iter() that will use this. So I'd just drop this patch...
Honza
> ---
> fs/ext4/ext4.h | 33 ++++++++++++++++++++++++++++++
> fs/ext4/extents.c | 16 +++++++--------
> fs/ext4/file.c | 52 +++++++++++++++++++++++------------------------
> fs/ext4/inode.c | 4 ++--
> fs/ext4/ioctl.c | 16 +++++++--------
> fs/ext4/super.c | 12 +++++------
> fs/ext4/xattr.c | 17 ++++++++--------
> 7 files changed, 92 insertions(+), 58 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 61987c106511..b4169a92e8d0 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -2960,6 +2960,39 @@ do { \
> #define EXT4_FREECLUSTERS_WATERMARK 0
> #endif
>
> +#define EXT4_IOLOCK_EXCL (1 << 0)
> +#define EXT4_IOLOCK_SHARED (1 << 1)
> +
> +static inline void ext4_ilock(struct inode *inode, unsigned int iolock)
> +{
> + if (iolock == EXT4_IOLOCK_EXCL)
> + inode_lock(inode);
> + else
> + inode_lock_shared(inode);
> +}
> +
> +static inline void ext4_iunlock(struct inode *inode, unsigned int iolock)
> +{
> + if (iolock == EXT4_IOLOCK_EXCL)
> + inode_unlock(inode);
> + else
> + inode_unlock_shared(inode);
> +}
> +
> +static inline int ext4_ilock_nowait(struct inode *inode, unsigned int iolock)
> +{
> + if (iolock == EXT4_IOLOCK_EXCL)
> + return inode_trylock(inode);
> + else
> + return inode_trylock_shared(inode);
> +}
> +
> +static inline void ext4_ilock_demote(struct inode *inode, unsigned int iolock)
> +{
> + BUG_ON(iolock != EXT4_IOLOCK_EXCL);
> + downgrade_write(&inode->i_rwsem);
> +}
> +
> /* Update i_disksize. Requires i_mutex to avoid races with truncate */
> static inline void ext4_update_i_disksize(struct inode *inode, loff_t newsize)
> {
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 0e8708b77da6..08dd57558533 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4754,7 +4754,7 @@ static long ext4_zero_range(struct file *file, loff_t offset,
> else
> max_blocks -= lblk;
>
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
>
> /*
> * Indirect files do not support unwritten extnets
> @@ -4864,7 +4864,7 @@ static long ext4_zero_range(struct file *file, loff_t offset,
>
> ext4_journal_stop(handle);
> out_mutex:
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> return ret;
> }
>
> @@ -4930,7 +4930,7 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
> if (mode & FALLOC_FL_KEEP_SIZE)
> flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
>
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
>
> /*
> * We only support preallocation for extent-based files only
> @@ -4961,7 +4961,7 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
> EXT4_I(inode)->i_sync_tid);
> }
> out:
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> trace_ext4_fallocate_exit(inode, offset, max_blocks, ret);
> return ret;
> }
> @@ -5509,7 +5509,7 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
> return ret;
> }
>
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
> /*
> * There is no need to overlap collapse range with EOF, in which case
> * it is effectively a truncate operation
> @@ -5608,7 +5608,7 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
> out_mmap:
> up_write(&EXT4_I(inode)->i_mmap_sem);
> out_mutex:
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> return ret;
> }
>
> @@ -5659,7 +5659,7 @@ int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len)
> return ret;
> }
>
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
> /* Currently just for extent based files */
> if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
> ret = -EOPNOTSUPP;
> @@ -5786,7 +5786,7 @@ int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len)
> out_mmap:
> up_write(&EXT4_I(inode)->i_mmap_sem);
> out_mutex:
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> return ret;
> }
>
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 977ac58dc718..ebe3f051598d 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -55,14 +55,14 @@ static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
> struct inode *inode = file_inode(iocb->ki_filp);
>
> if (iocb->ki_flags & IOCB_NOWAIT) {
> - if (!inode_trylock_shared(inode))
> + if (!ext4_ilock_nowait(inode, EXT4_IOLOCK_SHARED))
> return -EAGAIN;
> } else {
> - inode_lock_shared(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_SHARED);
> }
>
> if (!ext4_dio_supported(inode)) {
> - inode_unlock_shared(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_SHARED);
> /*
> * Fallback to buffered I/O if the operation being performed on
> * the inode is not supported by direct I/O. The IOCB_DIRECT
> @@ -76,7 +76,7 @@ static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
>
> ret = iomap_dio_rw(iocb, to, &ext4_iomap_ops, NULL,
> is_sync_kiocb(iocb));
> - inode_unlock_shared(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_SHARED);
>
> file_accessed(iocb->ki_filp);
> return ret;
> @@ -89,22 +89,23 @@ static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
> ssize_t ret;
>
> if (iocb->ki_flags & IOCB_NOWAIT) {
> - if (!inode_trylock_shared(inode))
> + if (!ext4_ilock_nowait(inode, EXT4_IOLOCK_SHARED))
> return -EAGAIN;
> } else {
> - inode_lock_shared(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_SHARED);
> }
> +
> /*
> * Recheck under inode lock - at this point we are sure it cannot
> * change anymore
> */
> if (!IS_DAX(inode)) {
> - inode_unlock_shared(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_SHARED);
> /* Fallback to buffered IO in case we cannot support DAX */
> return generic_file_read_iter(iocb, to);
> }
> ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
> - inode_unlock_shared(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_SHARED);
>
> file_accessed(iocb->ki_filp);
> return ret;
> @@ -244,7 +245,7 @@ static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
> if (iocb->ki_flags & IOCB_NOWAIT)
> return -EOPNOTSUPP;
>
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
> ret = ext4_write_checks(iocb, from);
> if (ret <= 0)
> goto out;
> @@ -254,7 +255,7 @@ static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
> current->backing_dev_info = NULL;
>
> out:
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> if (likely(ret > 0)) {
> iocb->ki_pos += ret;
> ret = generic_write_sync(iocb, ret);
> @@ -372,16 +373,17 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
> handle_t *handle;
> struct inode *inode = file_inode(iocb->ki_filp);
> bool extend = false, overwrite = false, unaligned_aio = false;
> + unsigned int iolock = EXT4_IOLOCK_EXCL;
>
> if (iocb->ki_flags & IOCB_NOWAIT) {
> - if (!inode_trylock(inode))
> + if (!ext4_ilock_nowait(inode, iolock))
> return -EAGAIN;
> } else {
> - inode_lock(inode);
> + ext4_ilock(inode, iolock);
> }
>
> if (!ext4_dio_supported(inode)) {
> - inode_unlock(inode);
> + ext4_iunlock(inode, iolock);
> /*
> * Fallback to buffered I/O if the inode does not support
> * direct I/O.
> @@ -391,7 +393,7 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
>
> ret = ext4_write_checks(iocb, from);
> if (ret <= 0) {
> - inode_unlock(inode);
> + ext4_iunlock(inode, iolock);
> return ret;
> }
>
> @@ -416,7 +418,8 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
> if (!unaligned_aio && ext4_overwrite_io(inode, offset, count) &&
> ext4_should_dioread_nolock(inode)) {
> overwrite = true;
> - downgrade_write(&inode->i_rwsem);
> + ext4_ilock_demote(inode, iolock);
> + iolock = EXT4_IOLOCK_SHARED;
> }
>
> if (offset + count > EXT4_I(inode)->i_disksize) {
> @@ -443,10 +446,7 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
> ret = ext4_handle_inode_extension(inode, offset, ret, count);
>
> out:
> - if (overwrite)
> - inode_unlock_shared(inode);
> - else
> - inode_unlock(inode);
> + ext4_iunlock(inode, iolock);
>
> if (ret >= 0 && iov_iter_count(from)) {
> ssize_t err;
> @@ -489,10 +489,10 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
> struct inode *inode = file_inode(iocb->ki_filp);
>
> if (iocb->ki_flags & IOCB_NOWAIT) {
> - if (!inode_trylock(inode))
> + if (!ext4_ilock_nowait(inode, EXT4_IOLOCK_EXCL))
> return -EAGAIN;
> } else {
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
> }
>
> ret = ext4_write_checks(iocb, from);
> @@ -524,7 +524,7 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
> if (extend)
> ret = ext4_handle_inode_extension(inode, offset, ret, count);
> out:
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> if (ret > 0)
> ret = generic_write_sync(iocb, ret);
> return ret;
> @@ -757,16 +757,16 @@ loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
> return generic_file_llseek_size(file, offset, whence,
> maxbytes, i_size_read(inode));
> case SEEK_HOLE:
> - inode_lock_shared(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_SHARED);
> offset = iomap_seek_hole(inode, offset,
> &ext4_iomap_report_ops);
> - inode_unlock_shared(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_SHARED);
> break;
> case SEEK_DATA:
> - inode_lock_shared(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_SHARED);
> offset = iomap_seek_data(inode, offset,
> &ext4_iomap_report_ops);
> - inode_unlock_shared(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_SHARED);
> break;
> }
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 381813205f99..39dcc22667a1 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3930,7 +3930,7 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
> return ret;
> }
>
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
>
> /* No need to punch hole beyond i_size */
> if (offset >= inode->i_size)
> @@ -4037,7 +4037,7 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
> out_dio:
> up_write(&EXT4_I(inode)->i_mmap_sem);
> out_mutex:
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> return ret;
> }
>
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index 0b7f316fd30f..43b7a23dc57b 100644
> --- a/fs/ext4/ioctl.c
> +++ b/fs/ext4/ioctl.c
> @@ -855,13 +855,13 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> if (err)
> return err;
>
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
> err = ext4_ioctl_check_immutable(inode,
> from_kprojid(&init_user_ns, ei->i_projid),
> flags);
> if (!err)
> err = ext4_ioctl_setflags(inode, flags);
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> mnt_drop_write_file(filp);
> return err;
> }
> @@ -892,7 +892,7 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> goto setversion_out;
> }
>
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
> handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
> if (IS_ERR(handle)) {
> err = PTR_ERR(handle);
> @@ -907,7 +907,7 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> ext4_journal_stop(handle);
>
> unlock_out:
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> setversion_out:
> mnt_drop_write_file(filp);
> return err;
> @@ -1026,9 +1026,9 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> * ext4_ext_swap_inode_data before we switch the
> * inode format to prevent read.
> */
> - inode_lock((inode));
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
> err = ext4_ext_migrate(inode);
> - inode_unlock((inode));
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> mnt_drop_write_file(filp);
> return err;
> }
> @@ -1272,7 +1272,7 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> if (err)
> return err;
>
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
> ext4_fill_fsxattr(inode, &old_fa);
> err = vfs_ioc_fssetxattr_check(inode, &old_fa, &fa);
> if (err)
> @@ -1287,7 +1287,7 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> goto out;
> err = ext4_ioctl_setproject(filp, fa.fsx_projid);
> out:
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> mnt_drop_write_file(filp);
> return err;
> }
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 7796e2ffc294..48b83b2cf0ad 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -2682,12 +2682,12 @@ static void ext4_orphan_cleanup(struct super_block *sb,
> __func__, inode->i_ino, inode->i_size);
> jbd_debug(2, "truncating inode %lu to %lld bytes\n",
> inode->i_ino, inode->i_size);
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
> truncate_inode_pages(inode->i_mapping, inode->i_size);
> ret = ext4_truncate(inode);
> if (ret)
> ext4_std_error(inode->i_sb, ret);
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> nr_truncates++;
> } else {
> if (test_opt(sb, DEBUG))
> @@ -5785,7 +5785,7 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id,
> * files. If this fails, we return success anyway since quotas
> * are already enabled and this is not a hard failure.
> */
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
> handle = ext4_journal_start(inode, EXT4_HT_QUOTA, 1);
> if (IS_ERR(handle))
> goto unlock_inode;
> @@ -5795,7 +5795,7 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id,
> ext4_mark_inode_dirty(handle, inode);
> ext4_journal_stop(handle);
> unlock_inode:
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> }
> return err;
> }
> @@ -5887,7 +5887,7 @@ static int ext4_quota_off(struct super_block *sb, int type)
> if (err || ext4_has_feature_quota(sb))
> goto out_put;
>
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
> /*
> * Update modification times of quota files when userspace can
> * start looking at them. If we fail, we return success anyway since
> @@ -5902,7 +5902,7 @@ static int ext4_quota_off(struct super_block *sb, int type)
> ext4_mark_inode_dirty(handle, inode);
> ext4_journal_stop(handle);
> out_unlock:
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> out_put:
> lockdep_set_quota_inode(inode, I_DATA_SEM_NORMAL);
> iput(inode);
> diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
> index 8966a5439a22..5c2dcc4c836a 100644
> --- a/fs/ext4/xattr.c
> +++ b/fs/ext4/xattr.c
> @@ -422,9 +422,9 @@ static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
> ext4_set_inode_state(inode, EXT4_STATE_LUSTRE_EA_INODE);
> ext4_xattr_inode_set_ref(inode, 1);
> } else {
> - inode_lock(inode);
> + ext4_ilock(inode, EXT4_IOLOCK_EXCL);
> inode->i_flags |= S_NOQUOTA;
> - inode_unlock(inode);
> + ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
> }
>
> *ea_inode = inode;
> @@ -976,7 +976,7 @@ static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode,
> u32 hash;
> int ret;
>
> - inode_lock(ea_inode);
> + ext4_ilock(ea_inode, EXT4_IOLOCK_EXCL);
>
> ret = ext4_reserve_inode_write(handle, ea_inode, &iloc);
> if (ret)
> @@ -1030,7 +1030,7 @@ static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode,
> ext4_warning_inode(ea_inode,
> "ext4_mark_iloc_dirty() failed ret=%d", ret);
> out:
> - inode_unlock(ea_inode);
> + ext4_iunlock(ea_inode, EXT4_IOLOCK_EXCL);
> return ret;
> }
>
> @@ -1380,10 +1380,11 @@ static int ext4_xattr_inode_write(handle_t *handle, struct inode *ea_inode,
> block += 1;
> }
>
> - inode_lock(ea_inode);
> + ext4_ilock(ea_inode, EXT4_IOLOCK_EXCL);
> i_size_write(ea_inode, wsize);
> ext4_update_i_disksize(ea_inode, wsize);
> - inode_unlock(ea_inode);
> + ext4_iunlock(ea_inode, EXT4_IOLOCK_EXCL);
> +
>
> ext4_mark_inode_dirty(handle, ea_inode);
>
> @@ -1432,9 +1433,9 @@ static struct inode *ext4_xattr_inode_create(handle_t *handle,
> */
> dquot_free_inode(ea_inode);
> dquot_drop(ea_inode);
> - inode_lock(ea_inode);
> + ext4_ilock(ea_inode, EXT4_IOLOCK_EXCL);
> ea_inode->i_flags |= S_NOQUOTA;
> - inode_unlock(ea_inode);
> + ext4_iunlock(ea_inode, EXT4_IOLOCK_EXCL);
> }
>
> return ea_inode;
> --
> 2.21.0
>
--
Jan Kara <jack@...e.com>
SUSE Labs, CR
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