Re: [PATCH AUTOSEL 5.8 25/42] ceph: fix inode number handling on arches with 32-bit ino_t

From: Ilya Dryomov
Date: Mon Aug 31 2020 - 12:08:47 EST

On Mon, Aug 31, 2020 at 5:30 PM Sasha Levin <sashal@xxxxxxxxxx> wrote:
>
> From: Jeff Layton <jlayton@xxxxxxxxxx>
>
> [ Upstream commit ebce3eb2f7ef9f6ef01a60874ebd232450107c9a ]
>
> Tuan and Ulrich mentioned that they were hitting a problem on s390x,
> which has a 32-bit ino_t value, even though it's a 64-bit arch (for
> historical reasons).
>
> I think the current handling of inode numbers in the ceph driver is
> wrong. It tries to use 32-bit inode numbers on 32-bit arches, but that's
> actually not a problem. 32-bit arches can deal with 64-bit inode numbers
> just fine when userland code is compiled with LFS support (the common
> case these days).
>
> What we really want to do is just use 64-bit numbers everywhere, unless
> someone has mounted with the ino32 mount option. In that case, we want
> to ensure that we hash the inode number down to something that will fit
> in 32 bits before presenting the value to userland.
>
> Add new helper functions that do this, and only do the conversion before
> presenting these values to userland in getattr and readdir.
>
> The inode table hashvalue is changed to just cast the inode number to
> unsigned long, as low-order bits are the most likely to vary anyway.
>
> While it's not strictly required, we do want to put something in
> inode->i_ino. Instead of basing it on BITS_PER_LONG, however, base it on
> the size of the ino_t type.
>
> NOTE: This is a user-visible change on 32-bit arches:
>
> 1/ inode numbers will be seen to have changed between kernel versions.
> 32-bit arches will see large inode numbers now instead of the hashed
> ones they saw before.
>
> 2/ any really old software not built with LFS support may start failing
> stat() calls with -EOVERFLOW on inode numbers >2^32. Nothing much we
> can do about these, but hopefully the intersection of people running
> such code on ceph will be very small.
>
> The workaround for both problems is to mount with "-o ino32".
>
> [ idryomov: changelog tweak ]
>
> URL: https://tracker.ceph.com/issues/46828
> Reported-by: Ulrich Weigand <Ulrich.Weigand@xxxxxxxxxx>
> Reported-and-Tested-by: Tuan Hoang1 <Tuan.Hoang1@xxxxxxx>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> Reviewed-by: "Yan, Zheng" <zyan@xxxxxxxxxx>
> Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
> fs/ceph/caps.c | 14 ++++-----
> fs/ceph/debugfs.c | 4 +--
> fs/ceph/dir.c | 31 ++++++++-----------
> fs/ceph/file.c | 4 +--
> fs/ceph/inode.c | 19 ++++++------
> fs/ceph/mds_client.h | 2 +-
> fs/ceph/quota.c | 4 +--
> fs/ceph/super.h | 73 +++++++++++++++++++++++---------------------
> 8 files changed, 74 insertions(+), 77 deletions(-)
>
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 972c13aa42259..1206a481c5fc7 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -886,8 +886,8 @@ int __ceph_caps_issued_mask(struct ceph_inode_info *ci, int mask, int touch)
> int have = ci->i_snap_caps;
>
> if ((have & mask) == mask) {
> - dout("__ceph_caps_issued_mask ino 0x%lx snap issued %s"
> - " (mask %s)\n", ci->vfs_inode.i_ino,
> + dout("__ceph_caps_issued_mask ino 0x%llx snap issued %s"
> + " (mask %s)\n", ceph_ino(&ci->vfs_inode),
> ceph_cap_string(have),
> ceph_cap_string(mask));
> return 1;
> @@ -898,8 +898,8 @@ int __ceph_caps_issued_mask(struct ceph_inode_info *ci, int mask, int touch)
> if (!__cap_is_valid(cap))
> continue;
> if ((cap->issued & mask) == mask) {
> - dout("__ceph_caps_issued_mask ino 0x%lx cap %p issued %s"
> - " (mask %s)\n", ci->vfs_inode.i_ino, cap,
> + dout("__ceph_caps_issued_mask ino 0x%llx cap %p issued %s"
> + " (mask %s)\n", ceph_ino(&ci->vfs_inode), cap,
> ceph_cap_string(cap->issued),
> ceph_cap_string(mask));
> if (touch)
> @@ -910,8 +910,8 @@ int __ceph_caps_issued_mask(struct ceph_inode_info *ci, int mask, int touch)
> /* does a combination of caps satisfy mask? */
> have |= cap->issued;
> if ((have & mask) == mask) {
> - dout("__ceph_caps_issued_mask ino 0x%lx combo issued %s"
> - " (mask %s)\n", ci->vfs_inode.i_ino,
> + dout("__ceph_caps_issued_mask ino 0x%llx combo issued %s"
> + " (mask %s)\n", ceph_ino(&ci->vfs_inode),
> ceph_cap_string(cap->issued),
> ceph_cap_string(mask));
> if (touch) {
> @@ -2870,7 +2870,7 @@ int ceph_get_caps(struct file *filp, int need, int want,
> struct cap_wait cw;
> DEFINE_WAIT_FUNC(wait, woken_wake_function);
>
> - cw.ino = inode->i_ino;
> + cw.ino = ceph_ino(inode);
> cw.tgid = current->tgid;
> cw.need = need;
> cw.want = want;
> diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
> index 070ed84813406..74747d8d48619 100644
> --- a/fs/ceph/debugfs.c
> +++ b/fs/ceph/debugfs.c
> @@ -212,7 +212,7 @@ static int caps_show_cb(struct inode *inode, struct ceph_cap *cap, void *p)
> {
> struct seq_file *s = p;
>
> - seq_printf(s, "0x%-17lx%-17s%-17s\n", inode->i_ino,
> + seq_printf(s, "0x%-17llx%-17s%-17s\n", ceph_ino(inode),
> ceph_cap_string(cap->issued),
> ceph_cap_string(cap->implemented));
> return 0;
> @@ -257,7 +257,7 @@ static int caps_show(struct seq_file *s, void *p)
>
> spin_lock(&mdsc->caps_list_lock);
> list_for_each_entry(cw, &mdsc->cap_wait_list, list) {
> - seq_printf(s, "%-13d0x%-17lx%-17s%-17s\n", cw->tgid, cw->ino,
> + seq_printf(s, "%-13d0x%-17llx%-17s%-17s\n", cw->tgid, cw->ino,
> ceph_cap_string(cw->need),
> ceph_cap_string(cw->want));
> }
> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> index 060bdcc5ce32c..040eaad9d0631 100644
> --- a/fs/ceph/dir.c
> +++ b/fs/ceph/dir.c
> @@ -259,9 +259,7 @@ static int __dcache_readdir(struct file *file, struct dir_context *ctx,
> dentry, dentry, d_inode(dentry));
> ctx->pos = di->offset;
> if (!dir_emit(ctx, dentry->d_name.name,
> - dentry->d_name.len,
> - ceph_translate_ino(dentry->d_sb,
> - d_inode(dentry)->i_ino),
> + dentry->d_name.len, ceph_present_inode(d_inode(dentry)),
> d_inode(dentry)->i_mode >> 12)) {
> dput(dentry);
> err = 0;
> @@ -324,18 +322,21 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
> /* always start with . and .. */
> if (ctx->pos == 0) {
> dout("readdir off 0 -> '.'\n");
> - if (!dir_emit(ctx, ".", 1,
> - ceph_translate_ino(inode->i_sb, inode->i_ino),
> + if (!dir_emit(ctx, ".", 1, ceph_present_inode(inode),
> inode->i_mode >> 12))
> return 0;
> ctx->pos = 1;
> }
> if (ctx->pos == 1) {
> - ino_t ino = parent_ino(file->f_path.dentry);
> + u64 ino;
> + struct dentry *dentry = file->f_path.dentry;
> +
> + spin_lock(&dentry->d_lock);
> + ino = ceph_present_inode(dentry->d_parent->d_inode);
> + spin_unlock(&dentry->d_lock);
> +
> dout("readdir off 1 -> '..'\n");
> - if (!dir_emit(ctx, "..", 2,
> - ceph_translate_ino(inode->i_sb, ino),
> - inode->i_mode >> 12))
> + if (!dir_emit(ctx, "..", 2, ino, inode->i_mode >> 12))
> return 0;
> ctx->pos = 2;
> }
> @@ -507,9 +508,6 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
> }
> for (; i < rinfo->dir_nr; i++) {
> struct ceph_mds_reply_dir_entry *rde = rinfo->dir_entries + i;
> - struct ceph_vino vino;
> - ino_t ino;
> - u32 ftype;
>
> BUG_ON(rde->offset < ctx->pos);
>
> @@ -519,13 +517,10 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
> rde->name_len, rde->name, &rde->inode.in);
>
> BUG_ON(!rde->inode.in);
> - ftype = le32_to_cpu(rde->inode.in->mode) >> 12;
> - vino.ino = le64_to_cpu(rde->inode.in->ino);
> - vino.snap = le64_to_cpu(rde->inode.in->snapid);
> - ino = ceph_vino_to_ino(vino);
>
> if (!dir_emit(ctx, rde->name, rde->name_len,
> - ceph_translate_ino(inode->i_sb, ino), ftype)) {
> + ceph_present_ino(inode->i_sb, le64_to_cpu(rde->inode.in->ino)),
> + le32_to_cpu(rde->inode.in->mode) >> 12)) {
> dout("filldir stopping us...\n");
> return 0;
> }
> @@ -1161,7 +1156,7 @@ static int ceph_unlink(struct inode *dir, struct dentry *dentry)
>
> if (try_async && op == CEPH_MDS_OP_UNLINK &&
> (req->r_dir_caps = get_caps_for_async_unlink(dir, dentry))) {
> - dout("async unlink on %lu/%.*s caps=%s", dir->i_ino,
> + dout("async unlink on %llu/%.*s caps=%s", ceph_ino(dir),
> dentry->d_name.len, dentry->d_name.name,
> ceph_cap_string(req->r_dir_caps));
> set_bit(CEPH_MDS_R_ASYNC, &req->r_req_flags);
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index 160644ddaeed7..26172bb90a459 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -630,8 +630,8 @@ static int ceph_finish_async_create(struct inode *dir, struct dentry *dentry,
> } else {
> struct dentry *dn;
>
> - dout("%s d_adding new inode 0x%llx to 0x%lx/%s\n", __func__,
> - vino.ino, dir->i_ino, dentry->d_name.name);
> + dout("%s d_adding new inode 0x%llx to 0x%llx/%s\n", __func__,
> + vino.ino, ceph_ino(dir), dentry->d_name.name);
> ceph_dir_clear_ordered(dir);
> ceph_init_inode_acls(inode, as_ctx);
> if (inode->i_state & I_NEW) {
> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> index 357c937699d56..d163fa96cb401 100644
> --- a/fs/ceph/inode.c
> +++ b/fs/ceph/inode.c
> @@ -41,8 +41,10 @@ static void ceph_inode_work(struct work_struct *work);
> */
> static int ceph_set_ino_cb(struct inode *inode, void *data)
> {
> - ceph_inode(inode)->i_vino = *(struct ceph_vino *)data;
> - inode->i_ino = ceph_vino_to_ino(*(struct ceph_vino *)data);
> + struct ceph_inode_info *ci = ceph_inode(inode);
> +
> + ci->i_vino = *(struct ceph_vino *)data;
> + inode->i_ino = ceph_vino_to_ino_t(ci->i_vino);
> inode_set_iversion_raw(inode, 0);
> return 0;
> }
> @@ -50,17 +52,14 @@ static int ceph_set_ino_cb(struct inode *inode, void *data)
> struct inode *ceph_get_inode(struct super_block *sb, struct ceph_vino vino)
> {
> struct inode *inode;
> - ino_t t = ceph_vino_to_ino(vino);
>
> - inode = iget5_locked(sb, t, ceph_ino_compare, ceph_set_ino_cb, &vino);
> + inode = iget5_locked(sb, (unsigned long)vino.ino, ceph_ino_compare,
> + ceph_set_ino_cb, &vino);
> if (!inode)
> return ERR_PTR(-ENOMEM);
> - if (inode->i_state & I_NEW)
> - dout("get_inode created new inode %p %llx.%llx ino %llx\n",
> - inode, ceph_vinop(inode), (u64)inode->i_ino);
>
> - dout("get_inode on %lu=%llx.%llx got %p\n", inode->i_ino, vino.ino,
> - vino.snap, inode);
> + dout("get_inode on %llu=%llx.%llx got %p new %d\n", ceph_present_inode(inode),
> + ceph_vinop(inode), inode, !!(inode->i_state & I_NEW));
> return inode;
> }
>
> @@ -2378,7 +2377,7 @@ int ceph_getattr(const struct path *path, struct kstat *stat,
> }
>
> generic_fillattr(inode, stat);
> - stat->ino = ceph_translate_ino(inode->i_sb, inode->i_ino);
> + stat->ino = ceph_present_inode(inode);
>
> /*
> * btime on newly-allocated inodes is 0, so if this is still set to
> diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
> index 5e0c4073a6bea..63c9cd1c28d6c 100644
> --- a/fs/ceph/mds_client.h
> +++ b/fs/ceph/mds_client.h
> @@ -369,7 +369,7 @@ struct ceph_quotarealm_inode {
>
> struct cap_wait {
> struct list_head list;
> - unsigned long ino;
> + u64 ino;
> pid_t tgid;
> int need;
> int want;
> diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c
> index 198ddde5c1e6a..cc2c4d40b0222 100644
> --- a/fs/ceph/quota.c
> +++ b/fs/ceph/quota.c
> @@ -23,12 +23,12 @@ static inline bool ceph_has_realms_with_quotas(struct inode *inode)
> {
> struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
> struct super_block *sb = mdsc->fsc->sb;
> + struct inode *root = d_inode(sb->s_root);
>
> if (atomic64_read(&mdsc->quotarealms_count) > 0)
> return true;
> /* if root is the real CephFS root, we don't have quota realms */
> - if (sb->s_root->d_inode &&
> - (sb->s_root->d_inode->i_ino == CEPH_INO_ROOT))
> + if (root && ceph_ino(root) == CEPH_INO_ROOT)
> return false;
> /* otherwise, we can't know for sure */
> return true;
> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> index 5a6cdd39bc103..2af3e06a6d0ce 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -457,15 +457,7 @@ ceph_vino(const struct inode *inode)
> return ceph_inode(inode)->i_vino;
> }
>
> -/*
> - * ino_t is <64 bits on many architectures, blech.
> - *
> - * i_ino (kernel inode) st_ino (userspace)
> - * i386 32 32
> - * x86_64+ino32 64 32
> - * x86_64 64 64
> - */
> -static inline u32 ceph_ino_to_ino32(__u64 vino)
> +static inline u32 ceph_ino_to_ino32(u64 vino)
> {
> u32 ino = vino & 0xffffffff;
> ino ^= vino >> 32;
> @@ -475,34 +467,17 @@ static inline u32 ceph_ino_to_ino32(__u64 vino)
> }
>
> /*
> - * kernel i_ino value
> + * Inode numbers in cephfs are 64 bits, but inode->i_ino is 32-bits on
> + * some arches. We generally do not use this value inside the ceph driver, but
> + * we do want to set it to something, so that generic vfs code has an
> + * appropriate value for tracepoints and the like.
> */
> -static inline ino_t ceph_vino_to_ino(struct ceph_vino vino)
> +static inline ino_t ceph_vino_to_ino_t(struct ceph_vino vino)
> {
> -#if BITS_PER_LONG == 32
> - return ceph_ino_to_ino32(vino.ino);
> -#else
> + if (sizeof(ino_t) == sizeof(u32))
> + return ceph_ino_to_ino32(vino.ino);
> return (ino_t)vino.ino;
> -#endif
> -}
> -
> -/*
> - * user-visible ino (stat, filldir)
> - */
> -#if BITS_PER_LONG == 32
> -static inline ino_t ceph_translate_ino(struct super_block *sb, ino_t ino)
> -{
> - return ino;
> -}
> -#else
> -static inline ino_t ceph_translate_ino(struct super_block *sb, ino_t ino)
> -{
> - if (ceph_test_mount_opt(ceph_sb_to_client(sb), INO32))
> - ino = ceph_ino_to_ino32(ino);
> - return ino;
> }
> -#endif
> -
>
> /* for printf-style formatting */
> #define ceph_vinop(i) ceph_inode(i)->i_vino.ino, ceph_inode(i)->i_vino.snap
> @@ -511,11 +486,34 @@ static inline u64 ceph_ino(struct inode *inode)
> {
> return ceph_inode(inode)->i_vino.ino;
> }
> +
> static inline u64 ceph_snap(struct inode *inode)
> {
> return ceph_inode(inode)->i_vino.snap;
> }
>
> +/**
> + * ceph_present_ino - format an inode number for presentation to userland
> + * @sb: superblock where the inode lives
> + * @ino: inode number to (possibly) convert
> + *
> + * If the user mounted with the ino32 option, then the 64-bit value needs
> + * to be converted to something that can fit inside 32 bits. Note that
> + * internal kernel code never uses this value, so this is entirely for
> + * userland consumption.
> + */
> +static inline u64 ceph_present_ino(struct super_block *sb, u64 ino)
> +{
> + if (unlikely(ceph_test_mount_opt(ceph_sb_to_client(sb), INO32)))
> + return ceph_ino_to_ino32(ino);
> + return ino;
> +}
> +
> +static inline u64 ceph_present_inode(struct inode *inode)
> +{
> + return ceph_present_ino(inode->i_sb, ceph_ino(inode));
> +}
> +
> static inline int ceph_ino_compare(struct inode *inode, void *data)
> {
> struct ceph_vino *pvino = (struct ceph_vino *)data;
> @@ -524,11 +522,16 @@ static inline int ceph_ino_compare(struct inode *inode, void *data)
> ci->i_vino.snap == pvino->snap;
> }
>
> +
> static inline struct inode *ceph_find_inode(struct super_block *sb,
> struct ceph_vino vino)
> {
> - ino_t t = ceph_vino_to_ino(vino);
> - return ilookup5(sb, t, ceph_ino_compare, &vino);
> + /*
> + * NB: The hashval will be run through the fs/inode.c hash function
> + * anyway, so there is no need to squash the inode number down to
> + * 32-bits first. Just use low-order bits on arches with 32-bit long.
> + */
> + return ilookup5(sb, (unsigned long)vino.ino, ceph_ino_compare, &vino);
> }
>
>
> --
> 2.25.1

Hi Sasha,

This is a user-visible change and wasn't marked for stable for that
reason. Please drop it.

Thanks,

Ilya