fs/: do not fallback to default_llseek() when readdir() uses BKL (ca572727) · Commits · 戴 / test

Do not use the fallback default_llseek() if the readdir operation of the filesystem still uses the big kernel lock. Since llseek() modifies file->f_pos of the directory directly it may need locking to not confuse readdir which usually uses file->f_pos directly as well Since the special characteristics of the BKL (unlocked on schedule) are not necessary in this case, the inode mutex can be used for locking as provided by generic_file_llseek(). This is only possible since all filesystems, except reiserfs, either use a directory as a flat file or with disk address offsets. Reiserfs on the other hand uses a 32bit hash off the filename as the offset so generic_file_llseek() can get used as well since the hash is always smaller than sb->s_maxbytes (= (512 << 32) - blocksize). Signed-off-by:

Jan Blunck <jblunck@suse.de> Acked-by:

Jan Kara <jack@suse.cz> Acked-by:

Anders Larsen <al@alarsen.net> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/autofs/root.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -28,6 +28,7 @@ static int autofs_root_mkdir(struct inode ,struct dentry ,int);
		static int autofs_root_ioctl(struct inode , struct file ,unsigned int,unsigned long);

		const struct file_operations autofs_root_operations = {
		.llseek = generic_file_llseek,
		.read = generic_read_dir,
		.readdir = autofs_root_readdir,
		.ioctl = autofs_root_ioctl,

fs/freevxfs/vxfs_lookup.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -57,6 +57,8 @@ const struct inode_operations vxfs_dir_inode_ops = {
		};

		const struct file_operations vxfs_dir_operations = {
		.llseek = generic_file_llseek,
		.read = generic_read_dir,
		.readdir = vxfs_readdir,
		};

fs/isofs/dir.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -272,6 +272,7 @@ static int isofs_readdir(struct file *filp,

		const struct file_operations isofs_dir_operations =
		{
		.llseek = generic_file_llseek,
		.read = generic_read_dir,
		.readdir = isofs_readdir,
		};

fs/ncpfs/dir.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -49,6 +49,7 @@ extern int ncp_symlink(struct inode , struct dentry , const char *);

		const struct file_operations ncp_dir_operations =
		{
		.llseek = generic_file_llseek,
		.read = generic_read_dir,
		.readdir = ncp_readdir,
		.unlocked_ioctl = ncp_ioctl,

fs/qnx4/dir.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -77,6 +77,7 @@ out:

		const struct file_operations qnx4_dir_operations =
		{
		.llseek = generic_file_llseek,
		.read = generic_read_dir,
		.readdir = qnx4_readdir,
		.fsync = simple_fsync,

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