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authorChris Down <chris@chrisdown.name>2020-08-06 23:20:25 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-07 11:33:24 -0700
commitea3271f7196c65ae5d3e1c7b3f733892c017dbd6 (patch)
treeb8e35df0da0afea4a25cfdaf2ceaf07d7db30f62 /mm/shmem.c
parente809d5f0b5c912fe981dce738f3283b2010665f0 (diff)
tmpfs: support 64-bit inums per-sb
The default is still set to inode32 for backwards compatibility, but system administrators can opt in to the new 64-bit inode numbers by either: 1. Passing inode64 on the command line when mounting, or 2. Configuring the kernel with CONFIG_TMPFS_INODE64=y The inode64 and inode32 names are used based on existing precedent from XFS. [hughd@google.com: Kconfig fixes] Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008011928010.13320@eggly.anvils Signed-off-by: Chris Down <chris@chrisdown.name> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox <willy@infradead.org> Cc: Jeff Layton <jlayton@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/8b23758d0c66b5e2263e08baf9c4b6a7565cbd8f.1594661218.git.chris@chrisdown.name Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/shmem.c')
-rw-r--r--mm/shmem.c65
1 files changed, 63 insertions, 2 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 585a82d87a92..c5c281893bb8 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -114,11 +114,13 @@ struct shmem_options {
kuid_t uid;
kgid_t gid;
umode_t mode;
+ bool full_inums;
int huge;
int seen;
#define SHMEM_SEEN_BLOCKS 1
#define SHMEM_SEEN_INODES 2
#define SHMEM_SEEN_HUGE 4
+#define SHMEM_SEEN_INUMS 8
};
#ifdef CONFIG_TMPFS
@@ -286,12 +288,17 @@ static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
ino = sbinfo->next_ino++;
if (unlikely(is_zero_ino(ino)))
ino = sbinfo->next_ino++;
- if (unlikely(ino > UINT_MAX)) {
+ if (unlikely(!sbinfo->full_inums &&
+ ino > UINT_MAX)) {
/*
* Emulate get_next_ino uint wraparound for
* compatibility
*/
- ino = 1;
+ if (IS_ENABLED(CONFIG_64BIT))
+ pr_warn("%s: inode number overflow on device %d, consider using inode64 mount option\n",
+ __func__, MINOR(sb->s_dev));
+ sbinfo->next_ino = 1;
+ ino = sbinfo->next_ino++;
}
*inop = ino;
}
@@ -304,6 +311,10 @@ static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
* unknown contexts. As such, use a per-cpu batched allocator
* which doesn't require the per-sb stat_lock unless we are at
* the batch boundary.
+ *
+ * We don't need to worry about inode{32,64} since SB_KERNMOUNT
+ * shmem mounts are not exposed to userspace, so we don't need
+ * to worry about things like glibc compatibility.
*/
ino_t *next_ino;
next_ino = per_cpu_ptr(sbinfo->ino_batch, get_cpu());
@@ -3397,6 +3408,8 @@ enum shmem_param {
Opt_nr_inodes,
Opt_size,
Opt_uid,
+ Opt_inode32,
+ Opt_inode64,
};
static const struct constant_table shmem_param_enums_huge[] = {
@@ -3416,6 +3429,8 @@ const struct fs_parameter_spec shmem_fs_parameters[] = {
fsparam_string("nr_inodes", Opt_nr_inodes),
fsparam_string("size", Opt_size),
fsparam_u32 ("uid", Opt_uid),
+ fsparam_flag ("inode32", Opt_inode32),
+ fsparam_flag ("inode64", Opt_inode64),
{}
};
@@ -3487,6 +3502,18 @@ static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
break;
}
goto unsupported_parameter;
+ case Opt_inode32:
+ ctx->full_inums = false;
+ ctx->seen |= SHMEM_SEEN_INUMS;
+ break;
+ case Opt_inode64:
+ if (sizeof(ino_t) < 8) {
+ return invalfc(fc,
+ "Cannot use inode64 with <64bit inums in kernel\n");
+ }
+ ctx->full_inums = true;
+ ctx->seen |= SHMEM_SEEN_INUMS;
+ break;
}
return 0;
@@ -3578,8 +3605,16 @@ static int shmem_reconfigure(struct fs_context *fc)
}
}
+ if ((ctx->seen & SHMEM_SEEN_INUMS) && !ctx->full_inums &&
+ sbinfo->next_ino > UINT_MAX) {
+ err = "Current inum too high to switch to 32-bit inums";
+ goto out;
+ }
+
if (ctx->seen & SHMEM_SEEN_HUGE)
sbinfo->huge = ctx->huge;
+ if (ctx->seen & SHMEM_SEEN_INUMS)
+ sbinfo->full_inums = ctx->full_inums;
if (ctx->seen & SHMEM_SEEN_BLOCKS)
sbinfo->max_blocks = ctx->blocks;
if (ctx->seen & SHMEM_SEEN_INODES) {
@@ -3619,6 +3654,29 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root)
if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
seq_printf(seq, ",gid=%u",
from_kgid_munged(&init_user_ns, sbinfo->gid));
+
+ /*
+ * Showing inode{64,32} might be useful even if it's the system default,
+ * since then people don't have to resort to checking both here and
+ * /proc/config.gz to confirm 64-bit inums were successfully applied
+ * (which may not even exist if IKCONFIG_PROC isn't enabled).
+ *
+ * We hide it when inode64 isn't the default and we are using 32-bit
+ * inodes, since that probably just means the feature isn't even under
+ * consideration.
+ *
+ * As such:
+ *
+ * +-----------------+-----------------+
+ * | TMPFS_INODE64=y | TMPFS_INODE64=n |
+ * +------------------+-----------------+-----------------+
+ * | full_inums=true | show | show |
+ * | full_inums=false | show | hide |
+ * +------------------+-----------------+-----------------+
+ *
+ */
+ if (IS_ENABLED(CONFIG_TMPFS_INODE64) || sbinfo->full_inums)
+ seq_printf(seq, ",inode%d", (sbinfo->full_inums ? 64 : 32));
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
if (sbinfo->huge)
@@ -3667,6 +3725,8 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
ctx->blocks = shmem_default_max_blocks();
if (!(ctx->seen & SHMEM_SEEN_INODES))
ctx->inodes = shmem_default_max_inodes();
+ if (!(ctx->seen & SHMEM_SEEN_INUMS))
+ ctx->full_inums = IS_ENABLED(CONFIG_TMPFS_INODE64);
} else {
sb->s_flags |= SB_NOUSER;
}
@@ -3684,6 +3744,7 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
}
sbinfo->uid = ctx->uid;
sbinfo->gid = ctx->gid;
+ sbinfo->full_inums = ctx->full_inums;
sbinfo->mode = ctx->mode;
sbinfo->huge = ctx->huge;
sbinfo->mpol = ctx->mpol;