From: Chuck Lever <chuck.lever@xxxxxxxxxx> The new directory offset helpers don't conform with the convention of getdents() returning no more entries once a directory file descriptor has reached the current end-of-directory. To address this, copy the logic from dcache_readdir() to mark the open directory file descriptor once EOD has been reached. Rewinding resets the mark. Reported-by: Tavian Barnes <tavianator@xxxxxxxxxxxxxx> Closes: https://lore.kernel.org/linux-fsdevel/20231113180616.2831430-1-tavianator@xxxxxxxxxxxxxx/ Fixes: 6faddda69f62 ("libfs: Add directory operations for stable offsets") Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> --- fs/libfs.c | 16 +++++++++++++--- include/linux/dcache.h | 1 + 2 files changed, 14 insertions(+), 3 deletions(-) Changes since RFC: - Keep file->private_data stable while directory descriptor remains open diff --git a/fs/libfs.c b/fs/libfs.c index e9440d55073c..d4df19b1b666 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -428,7 +428,7 @@ static bool offset_dir_emit(struct dir_context *ctx, struct dentry *dentry) inode->i_ino, fs_umode_to_dtype(inode->i_mode)); } -static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx) +static bool 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); @@ -437,7 +437,7 @@ static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx) while (true) { dentry = offset_find_next(&xas); if (!dentry) - break; + return true; if (!offset_dir_emit(ctx, dentry)) { dput(dentry); @@ -447,6 +447,7 @@ static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx) dput(dentry); ctx->pos = xas.xa_index + 1; } + return false; } /** @@ -472,6 +473,7 @@ static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx) */ static int offset_readdir(struct file *file, struct dir_context *ctx) { + struct dentry *cursor = file->private_data; struct dentry *dir = file->f_path.dentry; lockdep_assert_held(&d_inode(dir)->i_rwsem); @@ -479,11 +481,19 @@ static int offset_readdir(struct file *file, struct dir_context *ctx) if (!dir_emit_dots(file, ctx)) return 0; - offset_iterate_dir(d_inode(dir), ctx); + if (ctx->pos == 2) + cursor->d_flags &= ~DCACHE_EOD; + else if (cursor->d_flags & DCACHE_EOD) + return 0; + + if (offset_iterate_dir(d_inode(dir), ctx)) + cursor->d_flags |= DCACHE_EOD; return 0; } const struct file_operations simple_offset_dir_operations = { + .open = dcache_dir_open, + .release = dcache_dir_close, .llseek = offset_dir_llseek, .iterate_shared = offset_readdir, .read = generic_read_dir, diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 3da2f0545d5d..ee1757001583 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -208,6 +208,7 @@ struct dentry_operations { #define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */ #define DCACHE_NOKEY_NAME 0x02000000 /* Encrypted name encoded without key */ #define DCACHE_OP_REAL 0x04000000 +#define DCACHE_EOD 0x08000000 /* Reached end-of-directory */ #define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */ #define DCACHE_DENTRY_CURSOR 0x20000000
