From 1f60fbe7274918adb8db2f616e321890730ab7e3 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Sat, 23 Apr 2016 22:50:07 -0400 Subject: 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(). This was reverted earlier due to a typo in the original commit where I experimented with using signal_pending() instead of fatal_signal_pending(). The test was in the wrong place if we were going to return signal_pending() since we would end up returning duplicant entries. See 9f2394c9be47 for a more detailed explanation. Added fix as suggested by Linus to check for signal_pending() in in the filldir() functions. Reported-by: Benjamin LaHaise Google-Bug-Id: 27880676 Signed-off-by: Theodore Ts'o --- fs/readdir.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'fs/readdir.c') diff --git a/fs/readdir.c b/fs/readdir.c index e69ef3b79787..5f2d4bee5a73 100644 --- a/fs/readdir.c +++ b/fs/readdir.c @@ -169,6 +169,8 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen, } dirent = buf->previous; if (dirent) { + if (signal_pending(current)) + return -EINTR; if (__put_user(offset, &dirent->d_off)) goto efault; } @@ -248,6 +250,8 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen, return -EINVAL; dirent = buf->previous; if (dirent) { + if (signal_pending(current)) + return -EINTR; if (__put_user(offset, &dirent->d_off)) goto efault; } -- cgit v1.2.3 From 002354112f1e3cc7400ef48b853aefb90e801588 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 26 May 2016 00:05:12 -0400 Subject: restore killability of old mutex_lock_killable(&inode->i_mutex) users The ones that are taking it exclusive, that is... Signed-off-by: Al Viro --- fs/btrfs/ioctl.c | 18 +++++++----------- fs/overlayfs/readdir.c | 4 +--- fs/readdir.c | 12 ++++++------ 3 files changed, 14 insertions(+), 20 deletions(-) (limited to 'fs/readdir.c') diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 4e700694b741..c24473fac2fb 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -846,11 +846,9 @@ static noinline int btrfs_mksubvol(struct path *parent, struct dentry *dentry; int error; - inode_lock_nested(dir, I_MUTEX_PARENT); - // XXX: should've been - // mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT); - // if (error == -EINTR) - // return error; + error = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT); + if (error == -EINTR) + return error; dentry = lookup_one_len(name, parent->dentry, namelen); error = PTR_ERR(dentry); @@ -2377,11 +2375,9 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file, goto out; - inode_lock_nested(dir, I_MUTEX_PARENT); - // XXX: should've been - // err = mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT); - // if (err == -EINTR) - // goto out_drop_write; + err = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT); + if (err == -EINTR) + goto out_drop_write; dentry = lookup_one_len(vol_args->name, parent, namelen); if (IS_ERR(dentry)) { err = PTR_ERR(dentry); @@ -2571,7 +2567,7 @@ out_dput: dput(dentry); out_unlock_dir: inode_unlock(dir); -//out_drop_write: +out_drop_write: mnt_drop_write_file(file); out: kfree(vol_args); diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index da186ee4f846..9e79f6458dfb 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -218,9 +218,7 @@ static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd) cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); old_cred = override_creds(override_cred); - inode_lock(dir->d_inode); - err = 0; - // XXX: err = mutex_lock_killable(&dir->d_inode->i_mutex); + err = down_write_killable(&dir->d_inode->i_rwsem); if (!err) { while (rdd->first_maybe_whiteout) { p = rdd->first_maybe_whiteout; diff --git a/fs/readdir.c b/fs/readdir.c index 68ef06efe6bc..9d0212c374d6 100644 --- a/fs/readdir.c +++ b/fs/readdir.c @@ -35,13 +35,13 @@ int iterate_dir(struct file *file, struct dir_context *ctx) if (res) goto out; - if (shared) + if (shared) { inode_lock_shared(inode); - else - inode_lock(inode); - // res = mutex_lock_killable(&inode->i_mutex); - // if (res) - // goto out; + } else { + res = down_write_killable(&inode->i_rwsem); + if (res) + goto out; + } res = -ENOENT; if (!IS_DEADDIR(inode)) { -- cgit v1.2.3