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authorTheodore Ts'o <tytso@mit.edu>2012-08-17 09:48:17 -0400
committerTheodore Ts'o <tytso@mit.edu>2012-08-17 09:48:17 -0400
commitdf981d03eeff7971ac7e6ff37000bfa702327ef1 (patch)
tree4e944139b9e45c4af910c517b57f2d9bc7c81a1a /fs/ext4/namei.c
parent01fc48e8929e45e67527200017cff4e74e4ba054 (diff)
ext4: add max_dir_size_kb mount option
Very large directories can cause significant performance problems, or perhaps even invoke the OOM killer, if the process is running in a highly constrained memory environment (whether it is VM's with a small amount of memory or in a small memory cgroup). So it is useful, in cloud server/data center environments, to be able to set a filesystem-wide cap on the maximum size of a directory, to ensure that directories never get larger than a sane size. We do this via a new mount option, max_dir_size_kb. If there is an attempt to grow the directory larger than max_dir_size_kb, the system call will return ENOSPC instead. Google-Bug-Id: 6863013 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/namei.c')
-rw-r--r--fs/ext4/namei.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 2a42cc04466f..7450ff01c3c4 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -55,6 +55,13 @@ static struct buffer_head *ext4_append(handle_t *handle,
{
struct buffer_head *bh;
+ if (unlikely(EXT4_SB(inode->i_sb)->s_max_dir_size_kb &&
+ ((inode->i_size >> 10) >=
+ EXT4_SB(inode->i_sb)->s_max_dir_size_kb))) {
+ *err = -ENOSPC;
+ return NULL;
+ }
+
*block = inode->i_size >> inode->i_sb->s_blocksize_bits;
bh = ext4_bread(handle, inode, *block, 1, err);