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authorTheodore Ts'o <tytso@mit.edu>2016-03-30 22:36:24 -0400
committerTheodore Ts'o <tytso@mit.edu>2016-03-30 22:36:24 -0400
commit1028b55bafb7611dda1d8fed2aeca16a436b7dff (patch)
treec6881992855b87775897afe3712e6c72811856a0 /fs
parentde17e793b104d690e1d007dfc5cb6b4f649598ca (diff)
downloadlinux-1028b55bafb7611dda1d8fed2aeca16a436b7dff.tar.gz
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: Benjamin LaHaise <bcrl@kvack.org>
Google-Bug-Id: 27880676
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs')
-rw-r--r--fs/ext4/dir.c5
-rw-r--r--fs/ext4/namei.c5
2 files changed, 10 insertions, 0 deletions
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index 33f5e2a50cf8..ebfcb8999db2 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -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);
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 48e4b8907826..db98f89f737f 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -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);