Re: [PATCH 02/29] xfs: merge xfs_attr_remove into xfs_attr_set

Darrick J. Wong
2020-01-21T17:29:06Z

On Tue, Jan 14, 2020 at 09:10:24AM +0100, Christoph Hellwig wrote:
> The Linux xattr and acl APIs use a single call for set an remove. Modify
> the high-level XFS API to match that and let xfs_attr_set handle removing
> attributes as well. With a little bit of reordering this removes a lot
> of code.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/xfs/libxfs/xfs_attr.c | 174 +++++++++++++--------------------------
> fs/xfs/libxfs/xfs_attr.h | 2 -
> fs/xfs/xfs_acl.c | 33 +++-----
> fs/xfs/xfs_ioctl.c | 4 +-
> fs/xfs/xfs_xattr.c | 9 +-
> 5 files changed, 73 insertions(+), 149 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index e6149720ce02..04431ab9f5f5 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -350,149 +350,92 @@ xfs_attr_set(

xfs_attr_set() ought to gain a comment noting that a NULL @value
will remove the attribute.

> struct xfs_trans_res tres;
> int rsvd = (flags & ATTR_ROOT) != 0;
> int error, local;
> -
> - XFS_STATS_INC(mp, xs_attr_set);
> + unsigned int total;
>
> if (XFS_FORCED_SHUTDOWN(dp->i_mount))
> return -EIO;
>
> - error = xfs_attr_args_init(&args, dp, name, namelen, flags);
> - if (error)
> - return error;
> -
> - args.value = value;
> - args.valuelen = valuelen;
> - args.op_flags = XFS_DA_OP_ADDNAME | XFS_DA_OP_OKNOENT;
> - args.total = xfs_attr_calc_size(&args, &local);
> -
> error = xfs_qm_dqattach(dp);
> if (error)
> return error;
>
> - /*
> - * If the inode doesn't have an attribute fork, add one.
> - * (inode must not be locked when we call this routine)
> - */
> - if (XFS_IFORK_Q(dp) == 0) {
> - int sf_size = sizeof(xfs_attr_sf_hdr_t) +
> - XFS_ATTR_SF_ENTSIZE_BYNAME(args.namelen, valuelen);
> -
> - error = xfs_bmap_add_attrfork(dp, sf_size, rsvd);
> - if (error)
> - return error;
> - }
> -
> - tres.tr_logres = M_RES(mp)->tr_attrsetm.tr_logres +
> - M_RES(mp)->tr_attrsetrt.tr_logres * args.total;
> - tres.tr_logcount = XFS_ATTRSET_LOG_COUNT;
> - tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
> -
> - /*
> - * Root fork attributes can use reserved data blocks for this
> - * operation if necessary
> - */
> - error = xfs_trans_alloc(mp, &tres, args.total, 0,
> - rsvd ? XFS_TRANS_RESERVE : 0, &args.trans);
> + error = xfs_attr_args_init(&args, dp, name, namelen, flags);
> if (error)
> return error;
>
> - xfs_ilock(dp, XFS_ILOCK_EXCL);
> - error = xfs_trans_reserve_quota_nblks(args.trans, dp, args.total, 0,
> - rsvd ? XFS_QMOPT_RES_REGBLKS | XFS_QMOPT_FORCE_RES :
> - XFS_QMOPT_RES_REGBLKS);
> - if (error)
> - goto out_trans_cancel;
> -
> - xfs_trans_ijoin(args.trans, dp, 0);
> - error = xfs_attr_set_args(&args);
> - if (error)
> - goto out_trans_cancel;
> - if (!args.trans) {
> - /* shortform attribute has already been committed */
> - goto out_unlock;
> - }
> -
> - /*
> - * If this is a synchronous mount, make sure that the
> - * transaction goes to disk before returning to the user.
> - */
> - if (mp->m_flags & XFS_MOUNT_WSYNC)
> - xfs_trans_set_sync(args.trans);
> -
> - if ((flags & ATTR_KERNOTIME) == 0)
> - xfs_trans_ichgtime(args.trans, dp, XFS_ICHGTIME_CHG);
> + args.value = value;
> + args.valuelen = valuelen;
>
> /*
> - * Commit the last in the sequence of transactions.
> + * We have no control over the attribute names that userspace passes us
> + * to remove, so we have to allow the name lookup prior to attribute
> + * removal to fail as well.
> */
> - xfs_trans_log_inode(args.trans, dp, XFS_ILOG_CORE);
> - error = xfs_trans_commit(args.trans);
> -out_unlock:
> - xfs_iunlock(dp, XFS_ILOCK_EXCL);
> - return error;
> -
> -out_trans_cancel:
> - if (args.trans)
> - xfs_trans_cancel(args.trans);
> - goto out_unlock;
> -}
> + args.op_flags = XFS_DA_OP_OKNOENT;
>
> -/*
> - * Generic handler routine to remove a name from an attribute list.
> - * Transitions attribute list from Btree to shortform as necessary.
> - */
> -int
> -xfs_attr_remove(
> - struct xfs_inode *dp,
> - const unsigned char *name,
> - size_t namelen,
> - int flags)
> -{
> - struct xfs_mount *mp = dp->i_mount;
> - struct xfs_da_args args;
> - int error;
> + if (value) {
> + XFS_STATS_INC(mp, xs_attr_set);
>
> - XFS_STATS_INC(mp, xs_attr_remove);
> + args.op_flags |= XFS_DA_OP_ADDNAME;
> + args.total = xfs_attr_calc_size(&args, &local);
>
> - if (XFS_FORCED_SHUTDOWN(dp->i_mount))
> - return -EIO;
> + /*
> + * If the inode doesn't have an attribute fork, add one.
> + * (inode must not be locked when we call this routine)
> + */
> + if (XFS_IFORK_Q(dp) == 0) {
> + int sf_size = sizeof(struct xfs_attr_sf_hdr) +
> + XFS_ATTR_SF_ENTSIZE_BYNAME(args.namelen,
> + valuelen);
>
> - error = xfs_attr_args_init(&args, dp, name, namelen, flags);
> - if (error)
> - return error;
> + error = xfs_bmap_add_attrfork(dp, sf_size, rsvd);
> + if (error)
> + return error;
> + }
>
> - /*
> - * we have no control over the attribute names that userspace passes us
> - * to remove, so we have to allow the name lookup prior to attribute
> - * removal to fail.
> - */
> - args.op_flags = XFS_DA_OP_OKNOENT;
> + tres.tr_logres = M_RES(mp)->tr_attrsetm.tr_logres +
> + M_RES(mp)->tr_attrsetrt.tr_logres * args.total;
> + tres.tr_logcount = XFS_ATTRSET_LOG_COUNT;
> + tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
> + total = args.total;
> + } else {
> + XFS_STATS_INC(mp, xs_attr_remove);
>
> - error = xfs_qm_dqattach(dp);
> - if (error)
> - return error;
> + tres = M_RES(mp)->tr_attrrm;
> + total = XFS_ATTRRM_SPACE_RES(mp);
> + }
>
> /*
> * Root fork attributes can use reserved data blocks for this
> * operation if necessary
> */
> - error = xfs_trans_alloc(mp, &M_RES(mp)->tr_attrrm,
> - XFS_ATTRRM_SPACE_RES(mp), 0,
> - (flags & ATTR_ROOT) ? XFS_TRANS_RESERVE : 0,
> - &args.trans);
> + error = xfs_trans_alloc(mp, &tres, total, 0,
> + rsvd ? XFS_TRANS_RESERVE : 0, &args.trans);
> if (error)
> return error;
>
> xfs_ilock(dp, XFS_ILOCK_EXCL);
> - /*
> - * No need to make quota reservations here. We expect to release some
> - * blocks not allocate in the common case.
> - */
> xfs_trans_ijoin(args.trans, dp, 0);
> + if (value) {
> + unsigned int quota_flags = XFS_QMOPT_RES_REGBLKS;
>
> - error = xfs_attr_remove_args(&args);
> - if (error)
> - goto out;
> + if (rsvd)
> + quota_flags |= XFS_QMOPT_FORCE_RES;
> + error = xfs_trans_reserve_quota_nblks(args.trans, dp,
> + args.total, 0, quota_flags);
> + if (error)
> + goto out_trans_cancel;
> + error = xfs_attr_set_args(&args);
> + if (error)
> + goto out_trans_cancel;
> + /* shortform attribute has already been committed */
> + if (!args.trans)
> + goto out_unlock;
> + } else {
> + error = xfs_attr_remove_args(&args);
> + if (error)
> + goto out_trans_cancel;
> + }
>
> /*
> * If this is a synchronous mount, make sure that the
> @@ -509,15 +452,14 @@ xfs_attr_remove(
> */
> xfs_trans_log_inode(args.trans, dp, XFS_ILOG_CORE);
> error = xfs_trans_commit(args.trans);
> +out_unlock:
> xfs_iunlock(dp, XFS_ILOCK_EXCL);
> -
> return error;
>
> -out:
> +out_trans_cancel:
> if (args.trans)
> xfs_trans_cancel(args.trans);
> - xfs_iunlock(dp, XFS_ILOCK_EXCL);
> - return error;
> + goto out_unlock;
> }
>
> /*========================================================================
> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> index 71bcf1298e4c..db58a6c7dea5 100644
> --- a/fs/xfs/libxfs/xfs_attr.h
> +++ b/fs/xfs/libxfs/xfs_attr.h
> @@ -152,8 +152,6 @@ int xfs_attr_get(struct xfs_inode *ip, const unsigned char *name,
> int xfs_attr_set(struct xfs_inode *dp, const unsigned char *name,
> size_t namelen, unsigned char *value, int valuelen, int flags);
> int xfs_attr_set_args(struct xfs_da_args *args);
> -int xfs_attr_remove(struct xfs_inode *dp, const unsigned char *name,
> - size_t namelen, int flags);
> int xfs_attr_remove_args(struct xfs_da_args *args);
> int xfs_attr_list(struct xfs_inode *dp, char *buffer, int bufsize,
> int flags, struct attrlist_cursor_kern *cursor);
> diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c
> index cd743fad8478..2628f8530bf0 100644
> --- a/fs/xfs/xfs_acl.c
> +++ b/fs/xfs/xfs_acl.c
> @@ -168,6 +168,8 @@ __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
> {
> struct xfs_inode *ip = XFS_I(inode);
> unsigned char *ea_name;
> + struct xfs_acl *xfs_acl = NULL;
> + int len = 0;
> int error;
>
> switch (type) {
> @@ -184,9 +186,7 @@ __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
> }
>
> if (acl) {
> - struct xfs_acl *xfs_acl;
> - int len = XFS_ACL_MAX_SIZE(ip->i_mount);
> -
> + len = XFS_ACL_MAX_SIZE(ip->i_mount);
> xfs_acl = kmem_zalloc_large(len, 0);
> if (!xfs_acl)
> return -ENOMEM;
> @@ -196,26 +196,17 @@ __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
> /* subtract away the unused acl entries */
> len -= sizeof(struct xfs_acl_entry) *
> (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
> -
> - error = xfs_attr_set(ip, ea_name, strlen(ea_name),
> - (unsigned char *)xfs_acl, len, ATTR_ROOT);
> -
> - kmem_free(xfs_acl);
> - } else {
> - /*
> - * A NULL ACL argument means we want to remove the ACL.
> - */
> - error = xfs_attr_remove(ip, ea_name,
> - strlen(ea_name),
> - ATTR_ROOT);
> -
> - /*
> - * If the attribute didn't exist to start with that's fine.
> - */
> - if (error == -ENOATTR)
> - error = 0;
> }
>
> + error = xfs_attr_set(ip, ea_name, strlen(ea_name),
> + (unsigned char *)xfs_acl, len, ATTR_ROOT);
> + kmem_free(xfs_acl);
> +
> + /*
> + * If the attribute didn't exist to start with that's fine.
> + */
> + if (error == -ENOATTR)

if (!acl && error == -ENOATTR)

...because that's a behavior change w.r.t. error codes. I didn't see
anywhere in the attr code where setting a value would actually return
this, but let's not leave a logic bomb in case we ever do.

(The first thing my brain thought was, "ENOATTR on a set operation
suggests to me that something's seriously broken in the attr code; why
would you mask it?")

--D

> + error = 0;
> if (!error)
> set_cached_acl(inode, type, acl);
> return error;
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index d42de92cb283..8e35887f62fa 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -415,12 +415,10 @@ xfs_attrmulti_attr_remove(
> uint32_t flags)
> {
> int error;
> - size_t namelen;
>
> if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
> return -EPERM;
> - namelen = strlen(name);
> - error = xfs_attr_remove(XFS_I(inode), name, namelen, flags);
> + error = xfs_attr_set(XFS_I(inode), name, strlen(name), NULL, 0, flags);
> if (!error)
> xfs_forget_acl(inode, name, flags);
> return error;
> diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c
> index b0fedb543f97..1670bfbc9ad2 100644
> --- a/fs/xfs/xfs_xattr.c
> +++ b/fs/xfs/xfs_xattr.c
> @@ -69,7 +69,6 @@ xfs_xattr_set(const struct xattr_handler *handler, struct dentry *unused,
> int xflags = handler->flags;
> struct xfs_inode *ip = XFS_I(inode);
> int error;
> - size_t namelen = strlen(name);
>
> /* Convert Linux syscall to XFS internal ATTR flags */
> if (flags & XATTR_CREATE)
> @@ -77,14 +76,10 @@ xfs_xattr_set(const struct xattr_handler *handler, struct dentry *unused,
> if (flags & XATTR_REPLACE)
> xflags |= ATTR_REPLACE;
>
> - if (value)
> - error = xfs_attr_set(ip, name, namelen, (void *)value, size,
> - xflags);
> - else
> - error = xfs_attr_remove(ip, name, namelen, xflags);
> + error = xfs_attr_set(ip, (unsigned char *)name, strlen(name),
> + (void *)value, size, xflags);
> if (!error)
> xfs_forget_acl(inode, name, xflags);
> -
> return error;
> }
>
> --
> 2.24.1
>