#include <linux/fsnotify.h>
#include <linux/unicode.h>
#include <linux/fscrypt.h>
+#include <linux/pidfs.h>
#include <linux/uaccess.h>
};
EXPORT_SYMBOL(simple_dir_inode_operations);
-static void offset_set(struct dentry *dentry, u32 offset)
+/* 0 is '.', 1 is '..', so always start with offset 2 or more */
+enum {
+ DIR_OFFSET_MIN = 2,
+};
+
+static void offset_set(struct dentry *dentry, long offset)
{
- dentry->d_fsdata = (void *)((uintptr_t)(offset));
+ dentry->d_fsdata = (void *)offset;
}
-static u32 dentry2offset(struct dentry *dentry)
+static long dentry2offset(struct dentry *dentry)
{
- return (u32)((uintptr_t)(dentry->d_fsdata));
+ return (long)dentry->d_fsdata;
}
-static struct lock_class_key simple_offset_xa_lock;
+static struct lock_class_key simple_offset_lock_class;
/**
* simple_offset_init - initialize an offset_ctx
*/
void simple_offset_init(struct offset_ctx *octx)
{
- xa_init_flags(&octx->xa, XA_FLAGS_ALLOC1);
- lockdep_set_class(&octx->xa.xa_lock, &simple_offset_xa_lock);
-
- /* 0 is '.', 1 is '..', so always start with offset 2 */
- octx->next_offset = 2;
+ mt_init_flags(&octx->mt, MT_FLAGS_ALLOC_RANGE);
+ lockdep_set_class(&octx->mt.ma_lock, &simple_offset_lock_class);
+ octx->next_offset = DIR_OFFSET_MIN;
}
/**
* @octx: directory offset ctx to be updated
* @dentry: new dentry being added
*
- * Returns zero on success. @so_ctx and the dentry offset are updated.
+ * Returns zero on success. @octx and the dentry's offset are updated.
* Otherwise, a negative errno value is returned.
*/
int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry)
{
- static const struct xa_limit limit = XA_LIMIT(2, U32_MAX);
- u32 offset;
+ unsigned long offset;
int ret;
if (dentry2offset(dentry) != 0)
return -EBUSY;
- ret = xa_alloc_cyclic(&octx->xa, &offset, dentry, limit,
- &octx->next_offset, GFP_KERNEL);
+ ret = mtree_alloc_cyclic(&octx->mt, &offset, dentry, DIR_OFFSET_MIN,
+ LONG_MAX, &octx->next_offset, GFP_KERNEL);
if (ret < 0)
return ret;
*/
void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry)
{
- u32 offset;
+ long offset;
offset = dentry2offset(dentry);
if (offset == 0)
return;
- xa_erase(&octx->xa, offset);
+ mtree_erase(&octx->mt, offset);
offset_set(dentry, 0);
}
+/**
+ * simple_offset_empty - Check if a dentry can be unlinked
+ * @dentry: dentry to be tested
+ *
+ * Returns 0 if @dentry is a non-empty directory; otherwise returns 1.
+ */
+int simple_offset_empty(struct dentry *dentry)
+{
+ struct inode *inode = d_inode(dentry);
+ struct offset_ctx *octx;
+ struct dentry *child;
+ unsigned long index;
+ int ret = 1;
+
+ if (!inode || !S_ISDIR(inode->i_mode))
+ return ret;
+
+ index = DIR_OFFSET_MIN;
+ octx = inode->i_op->get_offset_ctx(inode);
+ mt_for_each(&octx->mt, child, index, LONG_MAX) {
+ spin_lock(&child->d_lock);
+ if (simple_positive(child)) {
+ spin_unlock(&child->d_lock);
+ ret = 0;
+ break;
+ }
+ spin_unlock(&child->d_lock);
+ }
+
+ return ret;
+}
+
/**
* simple_offset_rename_exchange - exchange rename with directory offsets
* @old_dir: parent of dentry being moved
{
struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir);
struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir);
- u32 old_index = dentry2offset(old_dentry);
- u32 new_index = dentry2offset(new_dentry);
+ long old_index = dentry2offset(old_dentry);
+ long new_index = dentry2offset(new_dentry);
int ret;
simple_offset_remove(old_ctx, old_dentry);
out_restore:
offset_set(old_dentry, old_index);
- xa_store(&old_ctx->xa, old_index, old_dentry, GFP_KERNEL);
+ mtree_store(&old_ctx->mt, old_index, old_dentry, GFP_KERNEL);
offset_set(new_dentry, new_index);
- xa_store(&new_ctx->xa, new_index, new_dentry, GFP_KERNEL);
+ mtree_store(&new_ctx->mt, new_index, new_dentry, GFP_KERNEL);
return ret;
}
*/
void simple_offset_destroy(struct offset_ctx *octx)
{
- xa_destroy(&octx->xa);
+ mtree_destroy(&octx->mt);
}
/**
/* In this case, ->private_data is protected by f_pos_lock */
file->private_data = NULL;
- return vfs_setpos(file, offset, U32_MAX);
+ return vfs_setpos(file, offset, LONG_MAX);
}
-static struct dentry *offset_find_next(struct xa_state *xas)
+static struct dentry *offset_find_next(struct offset_ctx *octx, loff_t offset)
{
+ MA_STATE(mas, &octx->mt, offset, offset);
struct dentry *child, *found = NULL;
rcu_read_lock();
- child = xas_next_entry(xas, U32_MAX);
+ child = mas_find(&mas, LONG_MAX);
if (!child)
goto out;
spin_lock(&child->d_lock);
static bool offset_dir_emit(struct dir_context *ctx, struct dentry *dentry)
{
- u32 offset = dentry2offset(dentry);
struct inode *inode = d_inode(dentry);
+ long offset = dentry2offset(dentry);
return ctx->actor(ctx, dentry->d_name.name, dentry->d_name.len, offset,
inode->i_ino, fs_umode_to_dtype(inode->i_mode));
static void *offset_iterate_dir(struct inode *inode, struct dir_context *ctx)
{
- struct offset_ctx *so_ctx = inode->i_op->get_offset_ctx(inode);
- XA_STATE(xas, &so_ctx->xa, ctx->pos);
+ struct offset_ctx *octx = inode->i_op->get_offset_ctx(inode);
struct dentry *dentry;
while (true) {
- dentry = offset_find_next(&xas);
+ dentry = offset_find_next(octx, ctx->pos);
if (!dentry)
return ERR_PTR(-ENOENT);
break;
}
+ ctx->pos = dentry2offset(dentry) + 1;
dput(dentry);
- ctx->pos = xas.xa_index + 1;
}
return NULL;
}
return 0;
/* In this case, ->private_data is protected by f_pos_lock */
- if (ctx->pos == 2)
+ if (ctx->pos == DIR_OFFSET_MIN)
file->private_data = NULL;
else if (file->private_data == ERR_PTR(-ENOENT))
return 0;
static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
const char *str, const struct qstr *name)
{
- const struct dentry *parent = READ_ONCE(dentry->d_parent);
- const struct inode *dir = READ_ONCE(parent->d_inode);
- const struct super_block *sb = dentry->d_sb;
- const struct unicode_map *um = sb->s_encoding;
- struct qstr qstr = QSTR_INIT(str, len);
+ const struct dentry *parent;
+ const struct inode *dir;
char strbuf[DNAME_INLINE_LEN];
- int ret;
+ struct qstr qstr;
+
+ /*
+ * Attempt a case-sensitive match first. It is cheaper and
+ * should cover most lookups, including all the sane
+ * applications that expect a case-sensitive filesystem.
+ *
+ * This comparison is safe under RCU because the caller
+ * guarantees the consistency between str and len. See
+ * __d_lookup_rcu_op_compare() for details.
+ */
+ if (len == name->len && !memcmp(str, name->name, len))
+ return 0;
+ parent = READ_ONCE(dentry->d_parent);
+ dir = READ_ONCE(parent->d_inode);
if (!dir || !IS_CASEFOLDED(dir))
- goto fallback;
+ return 1;
+
/*
* If the dentry name is stored in-line, then it may be concurrently
* modified by a rename. If this happens, the VFS will eventually retry
if (len <= DNAME_INLINE_LEN - 1) {
memcpy(strbuf, str, len);
strbuf[len] = 0;
- qstr.name = strbuf;
+ str = strbuf;
/* prevent compiler from optimizing out the temporary buffer */
barrier();
}
- ret = utf8_strncasecmp(um, name, &qstr);
- if (ret >= 0)
- return ret;
+ qstr.len = len;
+ qstr.name = str;
- if (sb_has_strict_encoding(sb))
- return -EINVAL;
-fallback:
- if (len != name->len)
- return 1;
- return !!memcmp(str, name->name, len);
+ return utf8_strncasecmp(dentry->d_sb->s_encoding, name, &qstr);
}
/**
const struct inode *dir = READ_ONCE(dentry->d_inode);
struct super_block *sb = dentry->d_sb;
const struct unicode_map *um = sb->s_encoding;
- int ret = 0;
+ int ret;
if (!dir || !IS_CASEFOLDED(dir))
return 0;
static const struct dentry_operations generic_ci_dentry_ops = {
.d_hash = generic_ci_d_hash,
.d_compare = generic_ci_d_compare,
-};
-#endif
-
#ifdef CONFIG_FS_ENCRYPTION
-static const struct dentry_operations generic_encrypted_dentry_ops = {
.d_revalidate = fscrypt_d_revalidate,
+#endif
};
#endif
-#if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
-static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
- .d_hash = generic_ci_d_hash,
- .d_compare = generic_ci_d_compare,
+#ifdef CONFIG_FS_ENCRYPTION
+static const struct dentry_operations generic_encrypted_dentry_ops = {
.d_revalidate = fscrypt_d_revalidate,
};
#endif
/**
- * generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry
- * @dentry: dentry to set ops on
- *
- * Casefolded directories need d_hash and d_compare set, so that the dentries
- * contained in them are handled case-insensitively. Note that these operations
- * are needed on the parent directory rather than on the dentries in it, and
- * while the casefolding flag can be toggled on and off on an empty directory,
- * dentry_operations can't be changed later. As a result, if the filesystem has
- * casefolding support enabled at all, we have to give all dentries the
- * casefolding operations even if their inode doesn't have the casefolding flag
- * currently (and thus the casefolding ops would be no-ops for now).
- *
- * Encryption works differently in that the only dentry operation it needs is
- * d_revalidate, which it only needs on dentries that have the no-key name flag.
- * The no-key flag can't be set "later", so we don't have to worry about that.
+ * generic_set_sb_d_ops - helper for choosing the set of
+ * filesystem-wide dentry operations for the enabled features
+ * @sb: superblock to be configured
*
- * Finally, to maximize compatibility with overlayfs (which isn't compatible
- * with certain dentry operations) and to avoid taking an unnecessary
- * performance hit, we use custom dentry_operations for each possible
- * combination rather than always installing all operations.
+ * Filesystems supporting casefolding and/or fscrypt can call this
+ * helper at mount-time to configure sb->s_d_op to best set of dentry
+ * operations required for the enabled features. The helper must be
+ * called after these have been configured, but before the root dentry
+ * is created.
*/
-void generic_set_encrypted_ci_d_ops(struct dentry *dentry)
+void generic_set_sb_d_ops(struct super_block *sb)
{
-#ifdef CONFIG_FS_ENCRYPTION
- bool needs_encrypt_ops = dentry->d_flags & DCACHE_NOKEY_NAME;
-#endif
#if IS_ENABLED(CONFIG_UNICODE)
- bool needs_ci_ops = dentry->d_sb->s_encoding;
-#endif
-#if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
- if (needs_encrypt_ops && needs_ci_ops) {
- d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops);
+ if (sb->s_encoding) {
+ sb->s_d_op = &generic_ci_dentry_ops;
return;
}
#endif
#ifdef CONFIG_FS_ENCRYPTION
- if (needs_encrypt_ops) {
- d_set_d_op(dentry, &generic_encrypted_dentry_ops);
- return;
- }
-#endif
-#if IS_ENABLED(CONFIG_UNICODE)
- if (needs_ci_ops) {
- d_set_d_op(dentry, &generic_ci_dentry_ops);
+ if (sb->s_cop) {
+ sb->s_d_op = &generic_encrypted_dentry_ops;
return;
}
#endif
}
-EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops);
+EXPORT_SYMBOL(generic_set_sb_d_ops);
/**
* inode_maybe_inc_iversion - increments i_version
return ts;
}
EXPORT_SYMBOL(simple_inode_init_ts);
+
+static inline struct dentry *get_stashed_dentry(struct dentry *stashed)
+{
+ struct dentry *dentry;
+
+ guard(rcu)();
+ dentry = READ_ONCE(stashed);
+ if (!dentry)
+ return NULL;
+ if (!lockref_get_not_dead(&dentry->d_lockref))
+ return NULL;
+ return dentry;
+}
+
+static struct dentry *prepare_anon_dentry(struct dentry **stashed,
+ unsigned long ino,
+ struct super_block *sb,
+ void *data)
+{
+ struct dentry *dentry;
+ struct inode *inode;
+ const struct stashed_operations *sops = sb->s_fs_info;
+
+ dentry = d_alloc_anon(sb);
+ if (!dentry)
+ return ERR_PTR(-ENOMEM);
+
+ inode = new_inode_pseudo(sb);
+ if (!inode) {
+ dput(dentry);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ inode->i_ino = ino;
+ inode->i_flags |= S_IMMUTABLE;
+ inode->i_mode = S_IFREG;
+ simple_inode_init_ts(inode);
+ sops->init_inode(inode, data);
+
+ /* Notice when this is changed. */
+ WARN_ON_ONCE(!S_ISREG(inode->i_mode));
+ WARN_ON_ONCE(!IS_IMMUTABLE(inode));
+
+ /* Store address of location where dentry's supposed to be stashed. */
+ dentry->d_fsdata = stashed;
+
+ /* @data is now owned by the fs */
+ d_instantiate(dentry, inode);
+ return dentry;
+}
+
+static struct dentry *stash_dentry(struct dentry **stashed,
+ struct dentry *dentry)
+{
+ guard(rcu)();
+ for (;;) {
+ struct dentry *old;
+
+ /* Assume any old dentry was cleared out. */
+ old = cmpxchg(stashed, NULL, dentry);
+ if (likely(!old))
+ return dentry;
+
+ /* Check if somebody else installed a reusable dentry. */
+ if (lockref_get_not_dead(&old->d_lockref))
+ return old;
+
+ /* There's an old dead dentry there, try to take it over. */
+ if (likely(try_cmpxchg(stashed, &old, dentry)))
+ return dentry;
+ }
+}
+
+/**
+ * path_from_stashed - create path from stashed or new dentry
+ * @stashed: where to retrieve or stash dentry
+ * @ino: inode number to use
+ * @mnt: mnt of the filesystems to use
+ * @data: data to store in inode->i_private
+ * @path: path to create
+ *
+ * The function tries to retrieve a stashed dentry from @stashed. If the dentry
+ * is still valid then it will be reused. If the dentry isn't able the function
+ * will allocate a new dentry and inode. It will then check again whether it
+ * can reuse an existing dentry in case one has been added in the meantime or
+ * update @stashed with the newly added dentry.
+ *
+ * Special-purpose helper for nsfs and pidfs.
+ *
+ * Return: On success zero and on failure a negative error is returned.
+ */
+int path_from_stashed(struct dentry **stashed, unsigned long ino,
+ struct vfsmount *mnt, void *data, struct path *path)
+{
+ struct dentry *dentry;
+ const struct stashed_operations *sops = mnt->mnt_sb->s_fs_info;
+
+ /* See if dentry can be reused. */
+ path->dentry = get_stashed_dentry(*stashed);
+ if (path->dentry) {
+ sops->put_data(data);
+ goto out_path;
+ }
+
+ /* Allocate a new dentry. */
+ dentry = prepare_anon_dentry(stashed, ino, mnt->mnt_sb, data);
+ if (IS_ERR(dentry)) {
+ sops->put_data(data);
+ return PTR_ERR(dentry);
+ }
+
+ /* Added a new dentry. @data is now owned by the filesystem. */
+ path->dentry = stash_dentry(stashed, dentry);
+ if (path->dentry != dentry)
+ dput(dentry);
+
+out_path:
+ WARN_ON_ONCE(path->dentry->d_fsdata != stashed);
+ WARN_ON_ONCE(d_inode(path->dentry)->i_private != data);
+ path->mnt = mntget(mnt);
+ return 0;
+}
+
+void stashed_dentry_prune(struct dentry *dentry)
+{
+ struct dentry **stashed = dentry->d_fsdata;
+ struct inode *inode = d_inode(dentry);
+
+ if (WARN_ON_ONCE(!stashed))
+ return;
+
+ if (!inode)
+ return;
+
+ /*
+ * Only replace our own @dentry as someone else might've
+ * already cleared out @dentry and stashed their own
+ * dentry in there.
+ */
+ cmpxchg(stashed, dentry, NULL);
+}
git.samba.org / sfrench / cifs-2.6.git / blobdiff