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@xxxxxxxxxx>
---
include/linux/shmem_fs.h | 2 +-
mm/shmem.c | 33 +++++++++++++++++----------------
2 files changed, 18 insertions(+), 17 deletions(-)
diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index 9b2d2faff1d0..6b0c626620f5 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -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 */
diff --git a/mm/shmem.c b/mm/shmem.c
index df3cabf54206..c39471384168 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -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);
}
}
@@ -3155,7 +3159,7 @@ 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 */
@@ -3815,13 +3819,13 @@ 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;
@@ -4002,21 +4006,17 @@ 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) {
@@ -4034,7 +4034,7 @@ 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;
}
@@ -4080,7 +4080,7 @@ 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;
}
/*
@@ -4211,7 +4211,8 @@ 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)
--
2.35.3
