Commit 1028b55b authored by Theodore Ts'o's avatar Theodore Ts'o

ext4: allow readdir()'s of large empty directories to be interrupted

If a directory has a large number of empty blocks, iterating over all
of them can take a long time, leading to scheduler warnings and users
getting irritated when they can't kill a process in the middle of one
of these long-running readdir operations.  Fix this by adding checks to
ext4_readdir() and ext4_htree_fill_tree().
Reported-by: default avatarBenjamin LaHaise <bcrl@kvack.org>
Google-Bug-Id: 27880676
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent de17e793
......@@ -150,6 +150,11 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
while (ctx->pos < inode->i_size) {
struct ext4_map_blocks map;
if (fatal_signal_pending(current)) {
err = -ERESTARTSYS;
goto errout;
}
cond_resched();
map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
map.m_len = 1;
err = ext4_map_blocks(NULL, inode, &map, 0);
......
......@@ -1107,6 +1107,11 @@ int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash,
}
while (1) {
if (signal_pending(current)) {
err = -ERESTARTSYS;
goto errout;
}
cond_resched();
block = dx_get_block(frame->at);
ret = htree_dirblock_to_tree(dir_file, dir, block, &hinfo,
start_hash, start_minor_hash);
......
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