[PATCH 14/14] Add ngnfs_dir_unlink(), ngfs_dir_rmdir(), and debugfs commands
Valerie Aurora
val at versity.com
Thu Feb 27 06:16:23 PST 2025
Allow removal of links to files and directories.
Signed-off-by: Valerie Aurora <val at versity.com>
---
cli/debugfs.c | 35 +++++++++++
shared/dir.c | 153 ++++++++++++++++++++++++++++++++++++++++++++++---
shared/dir.h | 2 +
shared/inode.c | 18 ++++++
shared/inode.h | 1 +
5 files changed, 201 insertions(+), 8 deletions(-)
diff --git a/cli/debugfs.c b/cli/debugfs.c
index fd6e2f0..dce23a9 100644
--- a/cli/debugfs.c
+++ b/cli/debugfs.c
@@ -209,6 +209,23 @@ static void cmd_readdir(struct debugfs_context *ctx, int argc, char **argv)
free(buf);
}
+static void cmd_rmdir(struct debugfs_context *ctx, int argc, char **argv)
+{
+ char *name;
+ int ret;
+
+ if (argc != 2) {
+ printf("usage: rmdir <pathname>\n");
+ return;
+ }
+
+ name = argv[1];
+
+ ret = ngnfs_dir_rmdir(ctx->nfi, ctx->cwd_ino, name, strlen(name));
+ if (ret < 0)
+ printf("rmdir error: "ENOF"\n", ENOA(-ret));
+}
+
static void cmd_stat(struct debugfs_context *ctx, int argc, char **argv)
{
struct ngnfs_dir_handle hdl;
@@ -273,6 +290,22 @@ static void cmd_sync(struct debugfs_context *ctx, int argc, char **argv)
printf("sync error: "ENOF"\n", ENOA(-ret));
}
+static void cmd_unlink(struct debugfs_context *ctx, int argc, char **argv)
+{
+ char *name;
+ int ret;
+
+ if (argc != 2) {
+ printf("usage: unlink <pathname>\n");
+ return;
+ }
+
+ name = argv[1];
+
+ ret = ngnfs_dir_unlink(ctx->nfi, ctx->cwd_ino, name, strlen(name));
+ if (ret < 0)
+ printf("unlink error: "ENOF"\n", ENOA(-ret));
+}
static struct command {
char *name;
@@ -285,8 +318,10 @@ static struct command {
{ "mkfs", cmd_mkfs, },
{ "quit", cmd_quit, },
{ "readdir", cmd_readdir, },
+ { "rmdir", cmd_rmdir, },
{ "stat", cmd_stat, },
{ "sync", cmd_sync, },
+ { "unlink", cmd_unlink, },
};
static int compar_cmd_names(const void *A, const void *B)
diff --git a/shared/dir.c b/shared/dir.c
index 5589e3f..482540b 100644
--- a/shared/dir.c
+++ b/shared/dir.c
@@ -76,6 +76,15 @@ static u64 name_hash(void *name, size_t name_len) {
return hash;
}
+/*
+ * Flags for communicating to the btree iteration function what tests it
+ * should do before carrying out the operation.
+ */
+enum {
+ NGNFS_DIRENT_WANT_DIR = 0x1,
+ NGNFS_DIRENT_WILL_MOVE = 0x2,
+};
+
/*
* These large dirent structs can fit a full sized name so that we can
* copy in and out any dirent as we work with them.
@@ -184,8 +193,8 @@ static inline int check_ifmt(struct ngnfs_inode *ninode, u32 ifmt, int err)
}
/*
- * Update a directory's inode to reflect creation. We can return errors
- * if the create should fail.
+ * Update a parent directory's inode to reflect creation or deletion of
+ * an entry. We can return errors if the create should fail.
*/
static int update_dir(struct ngnfs_txn_block *tblk, struct ngnfs_inode *dir,
struct dirent_args *da, int posneg)
@@ -194,12 +203,9 @@ static int update_dir(struct ngnfs_txn_block *tblk, struct ngnfs_inode *dir,
int ret;
if (S_ISDIR(le32_to_cpu(dir->mode))) {
- delta = posneg * 1;
- if ((le32_to_cpu(dir->nlink) + delta >= NGNFS_LINK_MAX)) {
- ret = -EMLINK;
+ ret = ngnfs_inode_update(tblk, dir, posneg);
+ if (ret < 0)
goto out;
- }
- ngnfs_tblk_assign(tblk, dir->nlink, cpu_to_le32(le32_to_cpu(dir->nlink) + delta));
}
/* dir i_size includes null termed names */
@@ -272,7 +278,6 @@ static int insert_dirent(struct ngnfs_fs_info *nfi, struct ngnfs_transaction *tx
&last, insert_dirent_wr, da);
}
-
/*
* Allocate a new inode and add a directory entry referencing it.
*/
@@ -656,3 +661,135 @@ int ngnfs_dir_get_handle(struct ngnfs_fs_info *nfi, u64 dir_ino, char *name, siz
out:
return ret;
}
+
+static int check_empty_dir(struct ngnfs_fs_info *nfi, struct ngnfs_transaction *txn, u64 ino,
+ struct ngnfs_inode_txn_ref *new)
+{
+ int ret;
+
+ ret = ngnfs_inode_get(nfi, txn, NBF_READ, ino, new);
+ if (ret < 0)
+ return ret;
+
+ if (le32_to_cpu(new->ninode->nlink) != 2)
+ return -ENOTEMPTY;
+
+ return 0;
+}
+
+/*
+ * Run final checks before removing a dirent, depending on whether we
+ * want a directory or if we are deleting or moving a dirent.
+ */
+static int check_remove_dirent(struct ngnfs_dirent *dent, struct dirent_args *da)
+{
+ if (!(da->flags & NGNFS_DIRENT_WANT_DIR)) {
+ if (dent->type == NGNFS_DT_DIR)
+ return -EISDIR;
+ else
+ return 0;
+ }
+
+ if (dent->type != NGNFS_DT_DIR)
+ return -ENOTDIR;
+
+ if (da->flags & NGNFS_DIRENT_WILL_MOVE)
+ return 0;
+
+ return check_empty_dir(da->nfi, da->txn, da->ino, &da->inode);
+}
+
+static int remove_dirent_wr(struct ngnfs_btree_key *key, void *val, size_t size, void *arg,
+ struct ngnfs_btree_op *op)
+{
+ struct ngnfs_dirent *dent = val;
+ struct dirent_args *da = arg;
+ int ret;
+
+ if (!dent)
+ return -ENOENT;
+
+ if (!names_equal(dent->name, dent->name_len, da->dent.name, da->dent.name_len))
+ return NGNFS_BTREE_ITER_CONTINUE;
+
+ /* ino and dtype needed for updating inode and parent directory */
+ da->ino = le64_to_cpu(dent->ino);
+ da->dtype = ngnfs_type_to_dtype(dent->type);
+
+ ret = check_remove_dirent(dent, da);
+ if (ret < 0)
+ return ret;
+
+ op->delete = 1;
+
+ return 0;
+}
+
+/*
+ * Remove a dirent item from a directory inode's dirent btree.
+ */
+static int remove_dirent(struct ngnfs_fs_info *nfi, struct ngnfs_transaction *txn,
+ struct ngnfs_inode_txn_ref *dir, struct dirent_args *da)
+{
+ struct ngnfs_btree_key key;
+ struct ngnfs_btree_key last;
+
+ init_dirent_key(&key, da->hash);
+ init_dirent_key(&last, da->hash | NGNFS_DIRENT_COLL_BIT);
+
+ return ngnfs_btree_write_iter(nfi, txn, dir->tblk, &dir->ninode->dirents, &key, &last,
+ remove_dirent_wr, da);
+}
+
+/*
+ * Unlink a directory entry. The goal is to walk the btree only once, so
+ * the check for directory/non-directory or directory emptiness is done
+ * in the btree iterator function.
+ */
+static int do_unlink(struct ngnfs_fs_info *nfi, u64 dir_ino, char *name, size_t name_len,
+ int flags)
+{
+ struct {
+ struct ngnfs_transaction txn;
+ struct ngnfs_inode_txn_ref dir;
+ struct dirent_args da;
+ u64 ino;
+ u64 nsec;
+ } *op;
+ int ret;
+
+ op = kmalloc(sizeof(*op), GFP_NOFS);
+ if (!op) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ ngnfs_txn_init(&op->txn);
+ op->nsec = ktime_to_ns(ktime_get_real());
+ init_dirent_args(nfi, &op->txn, &op->da, name, name_len, 0, 0, flags);
+
+ do {
+ ret = ngnfs_inode_get(nfi, &op->txn, NBF_WRITE, dir_ino, &op->dir) ?:
+ check_ifmt(op->dir.ninode, S_IFDIR, -ENOTDIR) ?:
+ remove_dirent(nfi, &op->txn, &op->dir, &op->da) ?:
+ ngnfs_inode_get(nfi, &op->txn, NBF_WRITE, op->da.ino, &op->da.inode) ?:
+ ngnfs_inode_update(op->da.inode.tblk, op->da.inode.ninode, -1) ?:
+ update_dir(op->dir.tblk, op->dir.ninode, &op->da, -1);
+
+ } while (ngnfs_txn_retry(nfi, &op->txn, &ret));
+
+ ngnfs_txn_teardown(nfi, &op->txn);
+ kfree(op);
+out:
+ return ret;
+}
+
+int ngnfs_dir_unlink(struct ngnfs_fs_info *nfi, u64 dir_ino, char *name, size_t name_len)
+{
+ return do_unlink(nfi, dir_ino, name, name_len, 0);
+}
+
+int ngnfs_dir_rmdir(struct ngnfs_fs_info *nfi, u64 dir_ino, char *name, size_t name_len)
+{
+ return do_unlink(nfi, dir_ino, name, name_len, NGNFS_DIRENT_WANT_DIR);
+}
diff --git a/shared/dir.h b/shared/dir.h
index 0115411..ec72c39 100644
--- a/shared/dir.h
+++ b/shared/dir.h
@@ -8,6 +8,8 @@ int ngnfs_dir_create(struct ngnfs_fs_info *nfi, u64 dir_ino, umode_t mode, char
size_t name_len);
int ngnfs_dir_mkdir(struct ngnfs_fs_info *nfi, u64 dir_ino, umode_t mode, char *name,
size_t name_len);
+int ngnfs_dir_unlink(struct ngnfs_fs_info *nfi, u64 dir_ino, char *name, size_t name_len);
+int ngnfs_dir_rmdir(struct ngnfs_fs_info *nfi, u64 dir_ino, char *name, size_t name_len);
/*
* ngnfs_dir_get_handle() returns a thing that lets userspace clients do
diff --git a/shared/inode.c b/shared/inode.c
index 03aadc7..03b4af6 100644
--- a/shared/inode.c
+++ b/shared/inode.c
@@ -51,6 +51,8 @@ int ngnfs_inode_init(struct ngnfs_inode_txn_ref *itref, u64 ino, u64 gen, u32 nl
int ngnfs_inode_get(struct ngnfs_fs_info *nfi, struct ngnfs_transaction *txn, nbf_t nbf, u64 ino,
struct ngnfs_inode_txn_ref *itref)
{
+ BUG_ON(ino == 0);
+
return ngnfs_txn_get_block(nfi, txn, ino, nbf, &itref->tblk, (void **)&itref->ninode);
}
@@ -96,3 +98,19 @@ int ngnfs_inode_read_copy(struct ngnfs_fs_info *nfi, u64 ino, void *buf, int siz
out:
return ret;
}
+
+/*
+ * Update an inode to reflect the addition or removal of a link to it.
+ */
+int ngnfs_inode_update(struct ngnfs_txn_block *tblk, struct ngnfs_inode *inode, int posneg)
+{
+ s32 delta;
+
+ delta = posneg * 1;
+ if ((le32_to_cpu(inode->nlink) + delta >= NGNFS_LINK_MAX))
+ return -EMLINK;
+
+ ngnfs_tblk_assign(tblk, inode->nlink, cpu_to_le32(le32_to_cpu(inode->nlink) + delta));
+
+ return 0;
+}
diff --git a/shared/inode.h b/shared/inode.h
index cafbdfb..73804f0 100644
--- a/shared/inode.h
+++ b/shared/inode.h
@@ -21,5 +21,6 @@ int ngnfs_inode_get(struct ngnfs_fs_info *nfi, struct ngnfs_transaction *txn, nb
int ngnfs_inode_alloc(struct ngnfs_fs_info *nfi, struct ngnfs_transaction *txn, u64 *ino,
struct ngnfs_inode_txn_ref *itref);
int ngnfs_inode_read_copy(struct ngnfs_fs_info *nfi, u64 ino, void *buf, int size);
+int ngnfs_inode_update(struct ngnfs_txn_block *tblk, struct ngnfs_inode *inode, int posneg);
#endif
--
2.48.1
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