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

From: Sasha Levin
Date: Sat Sep 05 2020 - 08:04:37 EST

On Mon, Aug 31, 2020 at 06:08:32PM +0200, Ilya Dryomov wrote:
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.

Dropped, thanks!

--
Thanks,
Sasha