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tmpfs: support 64-bit inums per-sb

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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>
This commit is contained in:
Chris Down
2020-08-06 23:20:25 -07:00
committed by Linus Torvalds
parent e809d5f0b5
commit ea3271f719
4 changed files with 103 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

65
mm/shmem.c
View File

@@ -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;