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-rw-r--r--mm/shmem.c468
1 files changed, 349 insertions, 119 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 8fa27e4e582..69edb45a9f2 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -99,6 +99,13 @@ static struct vfsmount *shm_mnt;
/* Pretend that each entry is of this size in directory's i_size */
#define BOGO_DIRENT_SIZE 20
+struct shmem_xattr {
+ struct list_head list; /* anchored by shmem_inode_info->xattr_list */
+ char *name; /* xattr name */
+ size_t size;
+ char value[0];
+};
+
/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
enum sgp_type {
SGP_READ, /* don't exceed i_size, don't allocate page */
@@ -822,6 +829,7 @@ static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
static void shmem_evict_inode(struct inode *inode)
{
struct shmem_inode_info *info = SHMEM_I(inode);
+ struct shmem_xattr *xattr, *nxattr;
if (inode->i_mapping->a_ops == &shmem_aops) {
truncate_inode_pages(inode->i_mapping, 0);
@@ -834,6 +842,11 @@ static void shmem_evict_inode(struct inode *inode)
mutex_unlock(&shmem_swaplist_mutex);
}
}
+
+ list_for_each_entry_safe(xattr, nxattr, &info->xattr_list, list) {
+ kfree(xattr->name);
+ kfree(xattr);
+ }
BUG_ON(inode->i_blocks);
shmem_free_inode(inode->i_sb);
end_writeback(inode);
@@ -852,7 +865,7 @@ static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_
static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
{
- struct inode *inode;
+ struct address_space *mapping;
unsigned long idx;
unsigned long size;
unsigned long limit;
@@ -875,8 +888,10 @@ static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, s
if (size > SHMEM_NR_DIRECT)
size = SHMEM_NR_DIRECT;
offset = shmem_find_swp(entry, ptr, ptr+size);
- if (offset >= 0)
+ if (offset >= 0) {
+ shmem_swp_balance_unmap();
goto found;
+ }
if (!info->i_indirect)
goto lost2;
@@ -917,6 +932,7 @@ static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, s
shmem_swp_unmap(ptr);
if (offset >= 0) {
shmem_dir_unmap(dir);
+ ptr = shmem_swp_map(subdir);
goto found;
}
}
@@ -928,8 +944,7 @@ lost2:
return 0;
found:
idx += offset;
- inode = igrab(&info->vfs_inode);
- spin_unlock(&info->lock);
+ ptr += offset;
/*
* Move _head_ to start search for next from here.
@@ -940,37 +955,18 @@ found:
*/
if (shmem_swaplist.next != &info->swaplist)
list_move_tail(&shmem_swaplist, &info->swaplist);
- mutex_unlock(&shmem_swaplist_mutex);
- error = 1;
- if (!inode)
- goto out;
/*
- * Charge page using GFP_KERNEL while we can wait.
- * Charged back to the user(not to caller) when swap account is used.
- * add_to_page_cache() will be called with GFP_NOWAIT.
+ * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
+ * but also to hold up shmem_evict_inode(): so inode cannot be freed
+ * beneath us (pagelock doesn't help until the page is in pagecache).
*/
- error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
- if (error)
- goto out;
- error = radix_tree_preload(GFP_KERNEL);
- if (error) {
- mem_cgroup_uncharge_cache_page(page);
- goto out;
- }
- error = 1;
-
- spin_lock(&info->lock);
- ptr = shmem_swp_entry(info, idx, NULL);
- if (ptr && ptr->val == entry.val) {
- error = add_to_page_cache_locked(page, inode->i_mapping,
- idx, GFP_NOWAIT);
- /* does mem_cgroup_uncharge_cache_page on error */
- } else /* we must compensate for our precharge above */
- mem_cgroup_uncharge_cache_page(page);
+ mapping = info->vfs_inode.i_mapping;
+ error = add_to_page_cache_locked(page, mapping, idx, GFP_NOWAIT);
+ /* which does mem_cgroup_uncharge_cache_page on error */
if (error == -EEXIST) {
- struct page *filepage = find_get_page(inode->i_mapping, idx);
+ struct page *filepage = find_get_page(mapping, idx);
error = 1;
if (filepage) {
/*
@@ -990,14 +986,8 @@ found:
swap_free(entry);
error = 1; /* not an error, but entry was found */
}
- if (ptr)
- shmem_swp_unmap(ptr);
+ shmem_swp_unmap(ptr);
spin_unlock(&info->lock);
- radix_tree_preload_end();
-out:
- unlock_page(page);
- page_cache_release(page);
- iput(inode); /* allows for NULL */
return error;
}
@@ -1009,6 +999,26 @@ int shmem_unuse(swp_entry_t entry, struct page *page)
struct list_head *p, *next;
struct shmem_inode_info *info;
int found = 0;
+ int error;
+
+ /*
+ * Charge page using GFP_KERNEL while we can wait, before taking
+ * the shmem_swaplist_mutex which might hold up shmem_writepage().
+ * Charged back to the user (not to caller) when swap account is used.
+ * add_to_page_cache() will be called with GFP_NOWAIT.
+ */
+ error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
+ if (error)
+ goto out;
+ /*
+ * Try to preload while we can wait, to not make a habit of
+ * draining atomic reserves; but don't latch on to this cpu,
+ * it's okay if sometimes we get rescheduled after this.
+ */
+ error = radix_tree_preload(GFP_KERNEL);
+ if (error)
+ goto uncharge;
+ radix_tree_preload_end();
mutex_lock(&shmem_swaplist_mutex);
list_for_each_safe(p, next, &shmem_swaplist) {
@@ -1016,17 +1026,19 @@ int shmem_unuse(swp_entry_t entry, struct page *page)
found = shmem_unuse_inode(info, entry, page);
cond_resched();
if (found)
- goto out;
+ break;
}
mutex_unlock(&shmem_swaplist_mutex);
- /*
- * Can some race bring us here? We've been holding page lock,
- * so I think not; but would rather try again later than BUG()
- */
+
+uncharge:
+ if (!found)
+ mem_cgroup_uncharge_cache_page(page);
+ if (found < 0)
+ error = found;
+out:
unlock_page(page);
page_cache_release(page);
-out:
- return (found < 0) ? found : 0;
+ return error;
}
/*
@@ -1064,7 +1076,25 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
else
swap.val = 0;
+ /*
+ * Add inode to shmem_unuse()'s list of swapped-out inodes,
+ * if it's not already there. Do it now because we cannot take
+ * mutex while holding spinlock, and must do so before the page
+ * is moved to swap cache, when its pagelock no longer protects
+ * the inode from eviction. But don't unlock the mutex until
+ * we've taken the spinlock, because shmem_unuse_inode() will
+ * prune a !swapped inode from the swaplist under both locks.
+ */
+ if (swap.val) {
+ mutex_lock(&shmem_swaplist_mutex);
+ if (list_empty(&info->swaplist))
+ list_add_tail(&info->swaplist, &shmem_swaplist);
+ }
+
spin_lock(&info->lock);
+ if (swap.val)
+ mutex_unlock(&shmem_swaplist_mutex);
+
if (index >= info->next_index) {
BUG_ON(!(info->flags & SHMEM_TRUNCATE));
goto unlock;
@@ -1084,21 +1114,10 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
delete_from_page_cache(page);
shmem_swp_set(info, entry, swap.val);
shmem_swp_unmap(entry);
- if (list_empty(&info->swaplist))
- inode = igrab(inode);
- else
- inode = NULL;
spin_unlock(&info->lock);
swap_shmem_alloc(swap);
BUG_ON(page_mapped(page));
swap_writepage(page, wbc);
- if (inode) {
- mutex_lock(&shmem_swaplist_mutex);
- /* move instead of add in case we're racing */
- list_move_tail(&info->swaplist, &shmem_swaplist);
- mutex_unlock(&shmem_swaplist_mutex);
- iput(inode);
- }
return 0;
}
@@ -1400,20 +1419,14 @@ repeat:
if (sbinfo->max_blocks) {
if (percpu_counter_compare(&sbinfo->used_blocks,
sbinfo->max_blocks) >= 0 ||
- shmem_acct_block(info->flags)) {
- spin_unlock(&info->lock);
- error = -ENOSPC;
- goto failed;
- }
+ shmem_acct_block(info->flags))
+ goto nospace;
percpu_counter_inc(&sbinfo->used_blocks);
spin_lock(&inode->i_lock);
inode->i_blocks += BLOCKS_PER_PAGE;
spin_unlock(&inode->i_lock);
- } else if (shmem_acct_block(info->flags)) {
- spin_unlock(&info->lock);
- error = -ENOSPC;
- goto failed;
- }
+ } else if (shmem_acct_block(info->flags))
+ goto nospace;
if (!filepage) {
int ret;
@@ -1493,6 +1506,24 @@ done:
error = 0;
goto out;
+nospace:
+ /*
+ * Perhaps the page was brought in from swap between find_lock_page
+ * and taking info->lock? We allow for that at add_to_page_cache_lru,
+ * but must also avoid reporting a spurious ENOSPC while working on a
+ * full tmpfs. (When filepage has been passed in to shmem_getpage, it
+ * is already in page cache, which prevents this race from occurring.)
+ */
+ if (!filepage) {
+ struct page *page = find_get_page(mapping, idx);
+ if (page) {
+ spin_unlock(&info->lock);
+ page_cache_release(page);
+ goto repeat;
+ }
+ }
+ spin_unlock(&info->lock);
+ error = -ENOSPC;
failed:
if (*pagep != filepage) {
unlock_page(filepage);
@@ -1597,6 +1628,7 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
spin_lock_init(&info->lock);
info->flags = flags & VM_NORESERVE;
INIT_LIST_HEAD(&info->swaplist);
+ INIT_LIST_HEAD(&info->xattr_list);
cache_no_acl(inode);
switch (mode & S_IFMT) {
@@ -1996,9 +2028,9 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
info = SHMEM_I(inode);
inode->i_size = len-1;
- if (len <= (char *)inode - (char *)info) {
+ if (len <= SHMEM_SYMLINK_INLINE_LEN) {
/* do it inline */
- memcpy(info, symname, len);
+ memcpy(info->inline_symlink, symname, len);
inode->i_op = &shmem_symlink_inline_operations;
} else {
error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
@@ -2024,7 +2056,7 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
{
- nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
+ nd_set_link(nd, SHMEM_I(dentry->d_inode)->inline_symlink);
return NULL;
}
@@ -2048,63 +2080,253 @@ static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *co
}
}
-static const struct inode_operations shmem_symlink_inline_operations = {
- .readlink = generic_readlink,
- .follow_link = shmem_follow_link_inline,
-};
-
-static const struct inode_operations shmem_symlink_inode_operations = {
- .readlink = generic_readlink,
- .follow_link = shmem_follow_link,
- .put_link = shmem_put_link,
-};
-
-#ifdef CONFIG_TMPFS_POSIX_ACL
+#ifdef CONFIG_TMPFS_XATTR
/*
- * Superblocks without xattr inode operations will get security.* xattr
- * support from the VFS "for free". As soon as we have any other xattrs
+ * Superblocks without xattr inode operations may get some security.* xattr
+ * support from the LSM "for free". As soon as we have any other xattrs
* like ACLs, we also need to implement the security.* handlers at
* filesystem level, though.
*/
-static size_t shmem_xattr_security_list(struct dentry *dentry, char *list,
- size_t list_len, const char *name,
- size_t name_len, int handler_flags)
+static int shmem_xattr_get(struct dentry *dentry, const char *name,
+ void *buffer, size_t size)
{
- return security_inode_listsecurity(dentry->d_inode, list, list_len);
-}
+ struct shmem_inode_info *info;
+ struct shmem_xattr *xattr;
+ int ret = -ENODATA;
-static int shmem_xattr_security_get(struct dentry *dentry, const char *name,
- void *buffer, size_t size, int handler_flags)
-{
- if (strcmp(name, "") == 0)
- return -EINVAL;
- return xattr_getsecurity(dentry->d_inode, name, buffer, size);
+ info = SHMEM_I(dentry->d_inode);
+
+ spin_lock(&info->lock);
+ list_for_each_entry(xattr, &info->xattr_list, list) {
+ if (strcmp(name, xattr->name))
+ continue;
+
+ ret = xattr->size;
+ if (buffer) {
+ if (size < xattr->size)
+ ret = -ERANGE;
+ else
+ memcpy(buffer, xattr->value, xattr->size);
+ }
+ break;
+ }
+ spin_unlock(&info->lock);
+ return ret;
}
-static int shmem_xattr_security_set(struct dentry *dentry, const char *name,
- const void *value, size_t size, int flags, int handler_flags)
+static int shmem_xattr_set(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
{
- if (strcmp(name, "") == 0)
- return -EINVAL;
- return security_inode_setsecurity(dentry->d_inode, name, value,
- size, flags);
+ struct inode *inode = dentry->d_inode;
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ struct shmem_xattr *xattr;
+ struct shmem_xattr *new_xattr = NULL;
+ size_t len;
+ int err = 0;
+
+ /* value == NULL means remove */
+ if (value) {
+ /* wrap around? */
+ len = sizeof(*new_xattr) + size;
+ if (len <= sizeof(*new_xattr))
+ return -ENOMEM;
+
+ new_xattr = kmalloc(len, GFP_KERNEL);
+ if (!new_xattr)
+ return -ENOMEM;
+
+ new_xattr->name = kstrdup(name, GFP_KERNEL);
+ if (!new_xattr->name) {
+ kfree(new_xattr);
+ return -ENOMEM;
+ }
+
+ new_xattr->size = size;
+ memcpy(new_xattr->value, value, size);
+ }
+
+ spin_lock(&info->lock);
+ list_for_each_entry(xattr, &info->xattr_list, list) {
+ if (!strcmp(name, xattr->name)) {
+ if (flags & XATTR_CREATE) {
+ xattr = new_xattr;
+ err = -EEXIST;
+ } else if (new_xattr) {
+ list_replace(&xattr->list, &new_xattr->list);
+ } else {
+ list_del(&xattr->list);
+ }
+ goto out;
+ }
+ }
+ if (flags & XATTR_REPLACE) {
+ xattr = new_xattr;
+ err = -ENODATA;
+ } else {
+ list_add(&new_xattr->list, &info->xattr_list);
+ xattr = NULL;
+ }
+out:
+ spin_unlock(&info->lock);
+ if (xattr)
+ kfree(xattr->name);
+ kfree(xattr);
+ return err;
}
-static const struct xattr_handler shmem_xattr_security_handler = {
- .prefix = XATTR_SECURITY_PREFIX,
- .list = shmem_xattr_security_list,
- .get = shmem_xattr_security_get,
- .set = shmem_xattr_security_set,
-};
static const struct xattr_handler *shmem_xattr_handlers[] = {
+#ifdef CONFIG_TMPFS_POSIX_ACL
&generic_acl_access_handler,
&generic_acl_default_handler,
- &shmem_xattr_security_handler,
+#endif
NULL
};
+
+static int shmem_xattr_validate(const char *name)
+{
+ struct { const char *prefix; size_t len; } arr[] = {
+ { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN },
+ { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN }
+ };
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(arr); i++) {
+ size_t preflen = arr[i].len;
+ if (strncmp(name, arr[i].prefix, preflen) == 0) {
+ if (!name[preflen])
+ return -EINVAL;
+ return 0;
+ }
+ }
+ return -EOPNOTSUPP;
+}
+
+static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
+ void *buffer, size_t size)
+{
+ int err;
+
+ /*
+ * If this is a request for a synthetic attribute in the system.*
+ * namespace use the generic infrastructure to resolve a handler
+ * for it via sb->s_xattr.
+ */
+ if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+ return generic_getxattr(dentry, name, buffer, size);
+
+ err = shmem_xattr_validate(name);
+ if (err)
+ return err;
+
+ return shmem_xattr_get(dentry, name, buffer, size);
+}
+
+static int shmem_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ int err;
+
+ /*
+ * If this is a request for a synthetic attribute in the system.*
+ * namespace use the generic infrastructure to resolve a handler
+ * for it via sb->s_xattr.
+ */
+ if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+ return generic_setxattr(dentry, name, value, size, flags);
+
+ err = shmem_xattr_validate(name);
+ if (err)
+ return err;
+
+ if (size == 0)
+ value = ""; /* empty EA, do not remove */
+
+ return shmem_xattr_set(dentry, name, value, size, flags);
+
+}
+
+static int shmem_removexattr(struct dentry *dentry, const char *name)
+{
+ int err;
+
+ /*
+ * If this is a request for a synthetic attribute in the system.*
+ * namespace use the generic infrastructure to resolve a handler
+ * for it via sb->s_xattr.
+ */
+ if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+ return generic_removexattr(dentry, name);
+
+ err = shmem_xattr_validate(name);
+ if (err)
+ return err;
+
+ return shmem_xattr_set(dentry, name, NULL, 0, XATTR_REPLACE);
+}
+
+static bool xattr_is_trusted(const char *name)
+{
+ return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
+}
+
+static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
+{
+ bool trusted = capable(CAP_SYS_ADMIN);
+ struct shmem_xattr *xattr;
+ struct shmem_inode_info *info;
+ size_t used = 0;
+
+ info = SHMEM_I(dentry->d_inode);
+
+ spin_lock(&info->lock);
+ list_for_each_entry(xattr, &info->xattr_list, list) {
+ size_t len;
+
+ /* skip "trusted." attributes for unprivileged callers */
+ if (!trusted && xattr_is_trusted(xattr->name))
+ continue;
+
+ len = strlen(xattr->name) + 1;
+ used += len;
+ if (buffer) {
+ if (size < used) {
+ used = -ERANGE;
+ break;
+ }
+ memcpy(buffer, xattr->name, len);
+ buffer += len;
+ }
+ }
+ spin_unlock(&info->lock);
+
+ return used;
+}
+#endif /* CONFIG_TMPFS_XATTR */
+
+static const struct inode_operations shmem_symlink_inline_operations = {
+ .readlink = generic_readlink,
+ .follow_link = shmem_follow_link_inline,
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = shmem_setxattr,
+ .getxattr = shmem_getxattr,
+ .listxattr = shmem_listxattr,
+ .removexattr = shmem_removexattr,
+#endif
+};
+
+static const struct inode_operations shmem_symlink_inode_operations = {
+ .readlink = generic_readlink,
+ .follow_link = shmem_follow_link,
+ .put_link = shmem_put_link,
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = shmem_setxattr,
+ .getxattr = shmem_getxattr,
+ .listxattr = shmem_listxattr,
+ .removexattr = shmem_removexattr,
#endif
+};
static struct dentry *shmem_get_parent(struct dentry *child)
{
@@ -2384,8 +2606,10 @@ int shmem_fill_super(struct super_block *sb, void *data, int silent)
sb->s_magic = TMPFS_MAGIC;
sb->s_op = &shmem_ops;
sb->s_time_gran = 1;
-#ifdef CONFIG_TMPFS_POSIX_ACL
+#ifdef CONFIG_TMPFS_XATTR
sb->s_xattr = shmem_xattr_handlers;
+#endif
+#ifdef CONFIG_TMPFS_POSIX_ACL
sb->s_flags |= MS_POSIXACL;
#endif
@@ -2483,11 +2707,13 @@ static const struct file_operations shmem_file_operations = {
static const struct inode_operations shmem_inode_operations = {
.setattr = shmem_notify_change,
.truncate_range = shmem_truncate_range,
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = shmem_setxattr,
+ .getxattr = shmem_getxattr,
+ .listxattr = shmem_listxattr,
+ .removexattr = shmem_removexattr,
+#endif
#ifdef CONFIG_TMPFS_POSIX_ACL
- .setxattr = generic_setxattr,
- .getxattr = generic_getxattr,
- .listxattr = generic_listxattr,
- .removexattr = generic_removexattr,
.check_acl = generic_check_acl,
#endif
@@ -2505,23 +2731,27 @@ static const struct inode_operations shmem_dir_inode_operations = {
.mknod = shmem_mknod,
.rename = shmem_rename,
#endif
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = shmem_setxattr,
+ .getxattr = shmem_getxattr,
+ .listxattr = shmem_listxattr,
+ .removexattr = shmem_removexattr,
+#endif
#ifdef CONFIG_TMPFS_POSIX_ACL
.setattr = shmem_notify_change,
- .setxattr = generic_setxattr,
- .getxattr = generic_getxattr,
- .listxattr = generic_listxattr,
- .removexattr = generic_removexattr,
.check_acl = generic_check_acl,
#endif
};
static const struct inode_operations shmem_special_inode_operations = {
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = shmem_setxattr,
+ .getxattr = shmem_getxattr,
+ .listxattr = shmem_listxattr,
+ .removexattr = shmem_removexattr,
+#endif
#ifdef CONFIG_TMPFS_POSIX_ACL
.setattr = shmem_notify_change,
- .setxattr = generic_setxattr,
- .getxattr = generic_getxattr,
- .listxattr = generic_listxattr,
- .removexattr = generic_removexattr,
.check_acl = generic_check_acl,
#endif
};
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-01-17 06:56:10 +0000