ext4: store cookie in private data

Store the cookie to detect concurrent seeks on directories in
file->private_data.

Link: https://lore.kernel.org/r/20240830-vfs-file-f_version-v1-11-6d3e4816aa7b@kernel.org
Acked-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index ff4514e4626bdbcfaf96bf48d91f6fb3cb32b512..13196afe55ce424e8c0828db8b9ce03aaefd67c4 100644 (file)
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -133,6 +133,7 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
        struct super_block *sb = inode->i_sb;
        struct buffer_head *bh = NULL;
        struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
+       struct dir_private_info *info = file->private_data;
 
        err = fscrypt_prepare_readdir(inode);
        if (err)
@@ -229,7 +230,7 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
                 * readdir(2), then we might be pointing to an invalid
                 * dirent right now.  Scan from the start of the block
                 * to make sure. */
-               if (!inode_eq_iversion(inode, file->f_version)) {
+               if (!inode_eq_iversion(inode, info->cookie)) {
                        for (i = 0; i < sb->s_blocksize && i < offset; ) {
                                de = (struct ext4_dir_entry_2 *)
                                        (bh->b_data + i);
@@ -249,7 +250,7 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
                        offset = i;
                        ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
                                | offset;
-                       file->f_version = inode_query_iversion(inode);
+                       info->cookie = inode_query_iversion(inode);
                }
 
                while (ctx->pos < inode->i_size
@@ -384,6 +385,7 @@ static inline loff_t ext4_get_htree_eof(struct file *filp)
 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
 {
        struct inode *inode = file->f_mapping->host;
+       struct dir_private_info *info = file->private_data;
        int dx_dir = is_dx_dir(inode);
        loff_t ret, htree_max = ext4_get_htree_eof(file);
 
@@ -392,7 +394,7 @@ static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
                                                    htree_max, htree_max);
        else
                ret = ext4_llseek(file, offset, whence);
-       file->f_version = inode_peek_iversion(inode) - 1;
+       info->cookie = inode_peek_iversion(inode) - 1;
        return ret;
 }
 
@@ -429,18 +431,15 @@ static void free_rb_tree_fname(struct rb_root *root)
        *root = RB_ROOT;
 }
 
-
-static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
-                                                          loff_t pos)
+static void ext4_htree_init_dir_info(struct file *filp, loff_t pos)
 {
-       struct dir_private_info *p;
-
-       p = kzalloc(sizeof(*p), GFP_KERNEL);
-       if (!p)
-               return NULL;
-       p->curr_hash = pos2maj_hash(filp, pos);
-       p->curr_minor_hash = pos2min_hash(filp, pos);
-       return p;
+       struct dir_private_info *p = filp->private_data;
+
+       if (is_dx_dir(file_inode(filp)) && !p->initialized) {
+               p->curr_hash = pos2maj_hash(filp, pos);
+               p->curr_minor_hash = pos2min_hash(filp, pos);
+               p->initialized = true;
+       }
 }
 
 void ext4_htree_free_dir_info(struct dir_private_info *p)
@@ -552,12 +551,7 @@ static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
        struct fname *fname;
        int ret = 0;
 
-       if (!info) {
-               info = ext4_htree_create_dir_info(file, ctx->pos);
-               if (!info)
-                       return -ENOMEM;
-               file->private_data = info;
-       }
+       ext4_htree_init_dir_info(file, ctx->pos);
 
        if (ctx->pos == ext4_get_htree_eof(file))
                return 0;       /* EOF */
@@ -590,10 +584,10 @@ static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
                 * cached entries.
                 */
                if ((!info->curr_node) ||
-                   !inode_eq_iversion(inode, file->f_version)) {
+                   !inode_eq_iversion(inode, info->cookie)) {
                        info->curr_node = NULL;
                        free_rb_tree_fname(&info->root);
-                       file->f_version = inode_query_iversion(inode);
+                       info->cookie = inode_query_iversion(inode);
                        ret = ext4_htree_fill_tree(file, info->curr_hash,
                                                   info->curr_minor_hash,
                                                   &info->next_hash);
@@ -664,7 +658,19 @@ int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
        return 0;
 }
 
+static int ext4_dir_open(struct inode *inode, struct file *file)
+{
+       struct dir_private_info *info;
+
+       info = kzalloc(sizeof(*info), GFP_KERNEL);
+       if (!info)
+               return -ENOMEM;
+       file->private_data = info;
+       return 0;
+}
+
 const struct file_operations ext4_dir_operations = {
+       .open           = ext4_dir_open,
        .llseek         = ext4_dir_llseek,
        .read           = generic_read_dir,
        .iterate_shared = ext4_readdir,

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 08acd152261ed87e0d4586cbecfe3b04b50f615d..d62a4b9b26ce43240d6b20438301cd5fc5c36949 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2553,6 +2553,8 @@ struct dir_private_info {
        __u32           curr_hash;
        __u32           curr_minor_hash;
        __u32           next_hash;
+       u64             cookie;
+       bool            initialized;
 };
 
 /* calculate the first block number of the group */

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index e7a09a99837b963f1c53fa65d0d3599d1298a19a..4282e12dc4050d63d0a5ee15e3b8bc0cdb316dc1 100644 (file)
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -1460,6 +1460,7 @@ int ext4_read_inline_dir(struct file *file,
        struct ext4_iloc iloc;
        void *dir_buf = NULL;
        int dotdot_offset, dotdot_size, extra_offset, extra_size;
+       struct dir_private_info *info = file->private_data;
 
        ret = ext4_get_inode_loc(inode, &iloc);
        if (ret)
@@ -1503,12 +1504,12 @@ int ext4_read_inline_dir(struct file *file,
        extra_size = extra_offset + inline_size;
 
        /*
-        * If the version has changed since the last call to
+        * If the cookie has changed since the last call to
         * readdir(2), then we might be pointing to an invalid
         * dirent right now.  Scan from the start of the inline
         * dir to make sure.
         */
-       if (!inode_eq_iversion(inode, file->f_version)) {
+       if (!inode_eq_iversion(inode, info->cookie)) {
                for (i = 0; i < extra_size && i < offset;) {
                        /*
                         * "." is with offset 0 and
@@ -1540,7 +1541,7 @@ int ext4_read_inline_dir(struct file *file,
                }
                offset = i;
                ctx->pos = offset;
-               file->f_version = inode_query_iversion(inode);
+               info->cookie = inode_query_iversion(inode);
        }
 
        while (ctx->pos < extra_size) {