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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1773160030; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=580OLnu98MzO5i32Lhtd2MCPaiQqex91cw2Qk/SXWUA=; b=hUbgDa15H6CTJg8eFmk5v+V2+lnMj6GuWlRALB9FfHXQmyXIGOmMce3OdphiTePD+nXqkv oI2IGhvnwmhbMHHiSJtj3Shhn7GKGcbYGO6uPeAfnvnEo84469gh8DlT19Vjd8kgvTGtfj FgLnVkBgF09N/nVoacQky/DZLJSIe3c= X-MC-Unique: -gb67MDpM1SwFimbAfFx1Q-1 X-Mimecast-MFC-AGG-ID: -gb67MDpM1SwFimbAfFx1Q_1773160026 From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [PULL 22/28] fuse: Make shared export state atomic Date: Tue, 10 Mar 2026 17:26:16 +0100 Message-ID: <20260310162622.333137-23-kwolf@redhat.com> In-Reply-To: <20260310162622.333137-1-kwolf@redhat.com> References: <20260310162622.333137-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" From: Hanna Czenczek The next commit is going to allow multi-threaded access to a FUSE export. In order to allow safe concurrent SETATTR operations that can modify the shared st_mode, st_uid, and st_gid, make any access to those fields atomic operations. Signed-off-by: Hanna Czenczek Message-ID: <20260309150856.26800-23-hreitz@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- block/export/fuse.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) diff --git a/block/export/fuse.c b/block/export/fuse.c index 1c794118393..fe1b6ad5ffc 100644 --- a/block/export/fuse.c +++ b/block/export/fuse.c @@ -156,6 +156,7 @@ typedef struct FuseExport { /* Whether allow_other was used as a mount option or not */ bool allow_other; =20 + /* All atomic */ mode_t st_mode; uid_t st_uid; gid_t st_gid; @@ -266,6 +267,7 @@ static int fuse_export_create(BlockExport *blk_exp, ERRP_GUARD(); /* ensure clean-up even with error_fatal */ FuseExport *exp =3D container_of(blk_exp, FuseExport, common); BlockExportOptionsFuse *args =3D &blk_exp_args->u.fuse; + uint32_t st_mode; int ret; =20 assert(blk_exp_args->type =3D=3D BLOCK_EXPORT_TYPE_FUSE); @@ -334,12 +336,13 @@ static int fuse_export_create(BlockExport *blk_exp, args->allow_other =3D FUSE_EXPORT_ALLOW_OTHER_AUTO; } =20 - exp->st_mode =3D S_IFREG | S_IRUSR; + st_mode =3D S_IFREG | S_IRUSR; if (exp->writable) { - exp->st_mode |=3D S_IWUSR; + st_mode |=3D S_IWUSR; } - exp->st_uid =3D getuid(); - exp->st_gid =3D getgid(); + qatomic_set(&exp->st_mode, st_mode); + qatomic_set(&exp->st_uid, getuid()); + qatomic_set(&exp->st_gid, getgid()); =20 if (args->allow_other =3D=3D FUSE_EXPORT_ALLOW_OTHER_AUTO) { /* Try allow_other =3D=3D true first, ignore errors */ @@ -817,10 +820,10 @@ fuse_co_getattr(FuseExport *exp, struct fuse_attr_out= *out) .attr_valid =3D 1, .attr =3D { .ino =3D 1, - .mode =3D exp->st_mode, + .mode =3D qatomic_read(&exp->st_mode), .nlink =3D 1, - .uid =3D exp->st_uid, - .gid =3D exp->st_gid, + .uid =3D qatomic_read(&exp->st_uid), + .gid =3D qatomic_read(&exp->st_gid), .size =3D length, .blksize =3D blk_bs(exp->common.blk)->bl.request_alignment, .blocks =3D allocated_blocks, @@ -903,15 +906,15 @@ fuse_co_setattr(FuseExport *exp, struct fuse_attr_out= *out, uint32_t to_set, =20 if (to_set & FATTR_MODE) { /* Ignore FUSE-supplied file type, only change the mode */ - exp->st_mode =3D (mode & 07777) | S_IFREG; + qatomic_set(&exp->st_mode, (mode & 07777) | S_IFREG); } =20 if (to_set & FATTR_UID) { - exp->st_uid =3D uid; + qatomic_set(&exp->st_uid, uid); } =20 if (to_set & FATTR_GID) { - exp->st_gid =3D gid; + qatomic_set(&exp->st_gid, gid); } =20 return fuse_co_getattr(exp, out); --=20 2.53.0