mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

tmpfs: track free_ispace instead of free_inodes 

In preparation for assigning some inode space to extended attributes,
keep track of free_ispace instead of number of free_inodes: as if one
tmpfs inode (and accompanying dentry) occupies very approximately 1KiB.

Unsigned long is large enough for free_ispace, on 64-bit and on 32-bit:
but take care to enforce the maximum.  And fix the nr_blocks maximum on
32-bit: S64_MAX would be too big for it there, so say LONG_MAX instead.

Delete the incorrect limited<->unlimited blocks/inodes comment above
shmem_reconfigure(): leave it to the error messages below to describe.

Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Message-Id: <4fe1739-d9e7-8dfd-5bce-12e7339711da@google.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Hugh Dickins 2023-08-08 21:32:21 -07:00 committed by Christian Brauner
parent 5de75970c9
commit e07c469e97
2 changed files with 18 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/shmem_fs.h
View File

@ -54,7 +54,7 @@ struct shmem_sb_info {
unsigned long max_blocks; /* How many blocks are allowed */
struct percpu_counter used_blocks; /* How many are allocated */
unsigned long max_inodes; /* How many inodes are allowed */
unsigned long free_inodes; /* How many are left for allocation */
unsigned long free_ispace; /* How much ispace left for allocation */
raw_spinlock_t stat_lock; /* Serialize shmem_sb_info changes */
umode_t mode; /* Mount mode for root directory */
unsigned char huge; /* Whether to try for hugepages */

33
mm/shmem.c
View File

@ -90,6 +90,9 @@ static struct vfsmount *shm_mnt;
/* Pretend that each entry is of this size in directory's i_size */
#define BOGO_DIRENT_SIZE 20
/* Pretend that one inode + its dentry occupy this much memory */
#define BOGO_INODE_SIZE 1024
/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
#define SHORT_SYMLINK_LEN 128
@ -137,7 +140,8 @@ static unsigned long shmem_default_max_inodes(void)
{
unsigned long nr_pages = totalram_pages();
return min(nr_pages - totalhigh_pages(), nr_pages / 2);
return min3(nr_pages - totalhigh_pages(), nr_pages / 2,
ULONG_MAX / BOGO_INODE_SIZE);
}
#endif
@ -331,11 +335,11 @@ static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
if (!(sb->s_flags & SB_KERNMOUNT)) {
raw_spin_lock(&sbinfo->stat_lock);
if (sbinfo->max_inodes) {
if (!sbinfo->free_inodes) {
if (sbinfo->free_ispace < BOGO_INODE_SIZE) {
raw_spin_unlock(&sbinfo->stat_lock);
return -ENOSPC;
}
sbinfo->free_inodes--;
sbinfo->free_ispace -= BOGO_INODE_SIZE;
}
if (inop) {
ino = sbinfo->next_ino++;
@ -394,7 +398,7 @@ static void shmem_free_inode(struct super_block *sb)
struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
if (sbinfo->max_inodes) {
raw_spin_lock(&sbinfo->stat_lock);
sbinfo->free_inodes++;
sbinfo->free_ispace += BOGO_INODE_SIZE;
raw_spin_unlock(&sbinfo->stat_lock);
}
}
@ -3158,7 +3162,7 @@ static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
}
if (sbinfo->max_inodes) {
buf->f_files = sbinfo->max_inodes;
buf->f_ffree = sbinfo->free_inodes;
buf->f_ffree = sbinfo->free_ispace / BOGO_INODE_SIZE;
}
/* else leave those fields 0 like simple_statfs */
@ -3818,13 +3822,13 @@ static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
break;
case Opt_nr_blocks:
ctx->blocks = memparse(param->string, &rest);
if (*rest || ctx->blocks > S64_MAX)
if (*rest || ctx->blocks > LONG_MAX)
goto bad_value;
ctx->seen |= SHMEM_SEEN_BLOCKS;
break;
case Opt_nr_inodes:
ctx->inodes = memparse(param->string, &rest);
if (*rest)
if (*rest || ctx->inodes > ULONG_MAX / BOGO_INODE_SIZE)
goto bad_value;
ctx->seen |= SHMEM_SEEN_INODES;
break;
@ -4005,21 +4009,17 @@ static int shmem_parse_options(struct fs_context *fc, void *data)
/*
* Reconfigure a shmem filesystem.
*
* Note that we disallow change from limited->unlimited blocks/inodes while any
* are in use; but we must separately disallow unlimited->limited, because in
* that case we have no record of how much is already in use.
*/
static int shmem_reconfigure(struct fs_context *fc)
{
struct shmem_options *ctx = fc->fs_private;
struct shmem_sb_info *sbinfo = SHMEM_SB(fc->root->d_sb);
unsigned long inodes;
unsigned long used_isp;
struct mempolicy *mpol = NULL;
const char *err;
raw_spin_lock(&sbinfo->stat_lock);
inodes = sbinfo->max_inodes - sbinfo->free_inodes;
used_isp = sbinfo->max_inodes * BOGO_INODE_SIZE - sbinfo->free_ispace;
if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) {
if (!sbinfo->max_blocks) {
@ -4037,7 +4037,7 @@ static int shmem_reconfigure(struct fs_context *fc)
err = "Cannot retroactively limit inodes";
goto out;
}
if (ctx->inodes < inodes) {
if (ctx->inodes * BOGO_INODE_SIZE < used_isp) {
err = "Too few inodes for current use";
goto out;
}
@ -4083,7 +4083,7 @@ static int shmem_reconfigure(struct fs_context *fc)
sbinfo->max_blocks = ctx->blocks;
if (ctx->seen & SHMEM_SEEN_INODES) {
sbinfo->max_inodes = ctx->inodes;
sbinfo->free_inodes = ctx->inodes - inodes;
sbinfo->free_ispace = ctx->inodes * BOGO_INODE_SIZE - used_isp;
}
/*
@ -4214,7 +4214,8 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
sb->s_flags |= SB_NOUSER;
#endif
sbinfo->max_blocks = ctx->blocks;
sbinfo->free_inodes = sbinfo->max_inodes = ctx->inodes;
sbinfo->max_inodes = ctx->inodes;
sbinfo->free_ispace = sbinfo->max_inodes * BOGO_INODE_SIZE;
if (sb->s_flags & SB_KERNMOUNT) {
sbinfo->ino_batch = alloc_percpu(ino_t);
if (!sbinfo->ino_batch)