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>
This commit is contained in:
Chris Down
Linus Torvalds
Родитель
e809d5f0b5
Коммит
ea3271f719
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@ -150,6 +150,22 @@ These options do not have any effect on remount. You can change these
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parameters with chmod(1), chown(1) and chgrp(1) on a mounted filesystem.
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tmpfs has a mount option to select whether it will wrap at 32- or 64-bit inode
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numbers:
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======= ========================
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inode64 Use 64-bit inode numbers
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inode32 Use 32-bit inode numbers
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======= ========================
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On a 32-bit kernel, inode32 is implicit, and inode64 is refused at mount time.
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On a 64-bit kernel, CONFIG_TMPFS_INODE64 sets the default. inode64 avoids the
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possibility of multiple files with the same inode number on a single device;
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but risks glibc failing with EOVERFLOW once 33-bit inode numbers are reached -
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if a long-lived tmpfs is accessed by 32-bit applications so ancient that
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opening a file larger than 2GiB fails with EINVAL.
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So 'mount -t tmpfs -o size=10G,nr_inodes=10k,mode=700 tmpfs /mytmpfs'
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will give you tmpfs instance on /mytmpfs which can allocate 10GB
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RAM/SWAP in 10240 inodes and it is only accessible by root.
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@ -161,3 +177,5 @@ RAM/SWAP in 10240 inodes and it is only accessible by root.
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Hugh Dickins, 4 June 2007
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:Updated:
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KOSAKI Motohiro, 16 Mar 2010
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:Updated:
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Chris Down, 13 July 2020
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21
fs/Kconfig
21
fs/Kconfig
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@ -201,6 +201,27 @@ config TMPFS_XATTR
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If unsure, say N.
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config TMPFS_INODE64
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bool "Use 64-bit ino_t by default in tmpfs"
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depends on TMPFS && 64BIT
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default n
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help
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tmpfs has historically used only inode numbers as wide as an unsigned
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int. In some cases this can cause wraparound, potentially resulting
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in multiple files with the same inode number on a single device. This
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option makes tmpfs use the full width of ino_t by default, without
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needing to specify the inode64 option when mounting.
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But if a long-lived tmpfs is to be accessed by 32-bit applications so
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ancient that opening a file larger than 2GiB fails with EINVAL, then
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the INODE64 config option and inode64 mount option risk operations
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failing with EOVERFLOW once 33-bit inode numbers are reached.
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To override this configured default, use the inode32 or inode64
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option when mounting.
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If unsure, say N.
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config HUGETLBFS
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bool "HugeTLB file system support"
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depends on X86 || IA64 || SPARC64 || (S390 && 64BIT) || \
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@ -36,6 +36,7 @@ struct shmem_sb_info {
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unsigned char huge; /* Whether to try for hugepages */
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kuid_t uid; /* Mount uid for root directory */
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kgid_t gid; /* Mount gid for root directory */
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bool full_inums; /* If i_ino should be uint or ino_t */
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ino_t next_ino; /* The next per-sb inode number to use */
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ino_t __percpu *ino_batch; /* The next per-cpu inode number to use */
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struct mempolicy *mpol; /* default memory policy for mappings */
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65
mm/shmem.c
65
mm/shmem.c
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@ -114,11 +114,13 @@ struct shmem_options {
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kuid_t uid;
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kgid_t gid;
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umode_t mode;
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bool full_inums;
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int huge;
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int seen;
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#define SHMEM_SEEN_BLOCKS 1
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#define SHMEM_SEEN_INODES 2
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#define SHMEM_SEEN_HUGE 4
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#define SHMEM_SEEN_INUMS 8
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};
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#ifdef CONFIG_TMPFS
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@ -286,12 +288,17 @@ static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
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ino = sbinfo->next_ino++;
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if (unlikely(is_zero_ino(ino)))
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ino = sbinfo->next_ino++;
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if (unlikely(ino > UINT_MAX)) {
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if (unlikely(!sbinfo->full_inums &&
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ino > UINT_MAX)) {
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/*
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* Emulate get_next_ino uint wraparound for
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* compatibility
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*/
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ino = 1;
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if (IS_ENABLED(CONFIG_64BIT))
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pr_warn("%s: inode number overflow on device %d, consider using inode64 mount option\n",
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__func__, MINOR(sb->s_dev));
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sbinfo->next_ino = 1;
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ino = sbinfo->next_ino++;
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}
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*inop = ino;
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}
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@ -304,6 +311,10 @@ static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
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* unknown contexts. As such, use a per-cpu batched allocator
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* which doesn't require the per-sb stat_lock unless we are at
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* the batch boundary.
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*
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* We don't need to worry about inode{32,64} since SB_KERNMOUNT
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* shmem mounts are not exposed to userspace, so we don't need
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* to worry about things like glibc compatibility.
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*/
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ino_t *next_ino;
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next_ino = per_cpu_ptr(sbinfo->ino_batch, get_cpu());
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@ -3397,6 +3408,8 @@ enum shmem_param {
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Opt_nr_inodes,
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Opt_size,
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Opt_uid,
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Opt_inode32,
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Opt_inode64,
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};
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static const struct constant_table shmem_param_enums_huge[] = {
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@ -3416,6 +3429,8 @@ const struct fs_parameter_spec shmem_fs_parameters[] = {
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fsparam_string("nr_inodes", Opt_nr_inodes),
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fsparam_string("size", Opt_size),
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fsparam_u32 ("uid", Opt_uid),
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fsparam_flag ("inode32", Opt_inode32),
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fsparam_flag ("inode64", Opt_inode64),
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{}
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};
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@ -3487,6 +3502,18 @@ static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
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break;
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}
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goto unsupported_parameter;
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case Opt_inode32:
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ctx->full_inums = false;
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ctx->seen |= SHMEM_SEEN_INUMS;
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break;
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case Opt_inode64:
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if (sizeof(ino_t) < 8) {
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return invalfc(fc,
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"Cannot use inode64 with <64bit inums in kernel\n");
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}
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ctx->full_inums = true;
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ctx->seen |= SHMEM_SEEN_INUMS;
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break;
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}
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return 0;
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@ -3578,8 +3605,16 @@ static int shmem_reconfigure(struct fs_context *fc)
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}
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}
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if ((ctx->seen & SHMEM_SEEN_INUMS) && !ctx->full_inums &&
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sbinfo->next_ino > UINT_MAX) {
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err = "Current inum too high to switch to 32-bit inums";
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goto out;
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}
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if (ctx->seen & SHMEM_SEEN_HUGE)
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sbinfo->huge = ctx->huge;
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if (ctx->seen & SHMEM_SEEN_INUMS)
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sbinfo->full_inums = ctx->full_inums;
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if (ctx->seen & SHMEM_SEEN_BLOCKS)
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sbinfo->max_blocks = ctx->blocks;
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if (ctx->seen & SHMEM_SEEN_INODES) {
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@ -3619,6 +3654,29 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root)
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if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
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seq_printf(seq, ",gid=%u",
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from_kgid_munged(&init_user_ns, sbinfo->gid));
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/*
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* Showing inode{64,32} might be useful even if it's the system default,
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* since then people don't have to resort to checking both here and
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* /proc/config.gz to confirm 64-bit inums were successfully applied
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* (which may not even exist if IKCONFIG_PROC isn't enabled).
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*
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* We hide it when inode64 isn't the default and we are using 32-bit
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* inodes, since that probably just means the feature isn't even under
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* consideration.
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*
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* As such:
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*
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* +-----------------+-----------------+
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* | TMPFS_INODE64=y | TMPFS_INODE64=n |
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* +------------------+-----------------+-----------------+
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* | full_inums=true | show | show |
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* | full_inums=false | show | hide |
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* +------------------+-----------------+-----------------+
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*
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*/
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if (IS_ENABLED(CONFIG_TMPFS_INODE64) || sbinfo->full_inums)
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seq_printf(seq, ",inode%d", (sbinfo->full_inums ? 64 : 32));
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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/* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
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if (sbinfo->huge)
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@ -3667,6 +3725,8 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
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ctx->blocks = shmem_default_max_blocks();
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if (!(ctx->seen & SHMEM_SEEN_INODES))
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ctx->inodes = shmem_default_max_inodes();
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if (!(ctx->seen & SHMEM_SEEN_INUMS))
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ctx->full_inums = IS_ENABLED(CONFIG_TMPFS_INODE64);
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} else {
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sb->s_flags |= SB_NOUSER;
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}
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@ -3684,6 +3744,7 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
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}
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sbinfo->uid = ctx->uid;
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sbinfo->gid = ctx->gid;
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sbinfo->full_inums = ctx->full_inums;
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sbinfo->mode = ctx->mode;
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sbinfo->huge = ctx->huge;
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sbinfo->mpol = ctx->mpol;
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