From ea3271f7196c65ae5d3e1c7b3f733892c017dbd6 Mon Sep 17 00:00:00 2001 From: Chris Down Date: Thu, 6 Aug 2020 23:20:25 -0700 Subject: 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 Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Reviewed-by: Amir Goldstein Acked-by: Hugh Dickins Cc: Al Viro Cc: Matthew Wilcox Cc: Jeff Layton Cc: Johannes Weiner Cc: Tejun Heo Link: http://lkml.kernel.org/r/8b23758d0c66b5e2263e08baf9c4b6a7565cbd8f.1594661218.git.chris@chrisdown.name Signed-off-by: Linus Torvalds --- mm/shmem.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 63 insertions(+), 2 deletions(-) (limited to 'mm/shmem.c') 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; -- cgit v1.2.3