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Revision 7bf811a595a895b7a886dcf218d0d34f97df76dc authored by Josef Bacik on 08 October 2013, 02:11:09 UTC, committed by Chris Mason on 11 October 2013, 01:27:56 UTC 
Btrfs: limit delalloc pages outside of find_delalloc_range
 
Liu fixed part of this problem and unfortunately I steered him in slightly the
wrong direction and so didn't completely fix the problem.  The problem is we
limit the size of the delalloc range we are looking for to max bytes and then we
try to lock that range.  If we fail to lock the pages in that range we will
shrink the max bytes to a single page and re loop.  However if our first page is
inside of the delalloc range then we will end up limiting the end of the range
to a period before our first page.  This is illustrated below

[0 -------- delalloc range --------- 256mb]
                                  [page]

So find_delalloc_range will return with delalloc_start as 0 and end as 128mb,
and then we will notice that delalloc_start < *start and adjust it up, but not
adjust delalloc_end up, so things go sideways.  To fix this we need to not limit
the max bytes in find_delalloc_range, but in find_lock_delalloc_range and that
way we don't end up with this confusion.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
1 parent 4871c15
Raw File
mount.h 
/*
 *
 * Definitions for mount interface. This describes the in the kernel build 
 * linkedlist with mounted filesystems.
 *
 * Author:  Marco van Wieringen <mvw@planets.elm.net>
 *
 */
#ifndef _LINUX_MOUNT_H
#define _LINUX_MOUNT_H

#include <linux/types.h>
#include <linux/list.h>
#include <linux/nodemask.h>
#include <linux/spinlock.h>
#include <linux/seqlock.h>
#include <linux/atomic.h>

struct super_block;
struct vfsmount;
struct dentry;
struct mnt_namespace;

#define MNT_NOSUID	0x01
#define MNT_NODEV	0x02
#define MNT_NOEXEC	0x04
#define MNT_NOATIME	0x08
#define MNT_NODIRATIME	0x10
#define MNT_RELATIME	0x20
#define MNT_READONLY	0x40	/* does the user want this to be r/o? */

#define MNT_SHRINKABLE	0x100
#define MNT_WRITE_HOLD	0x200

#define MNT_SHARED	0x1000	/* if the vfsmount is a shared mount */
#define MNT_UNBINDABLE	0x2000	/* if the vfsmount is a unbindable mount */
/*
 * MNT_SHARED_MASK is the set of flags that should be cleared when a
 * mount becomes shared.  Currently, this is only the flag that says a
 * mount cannot be bind mounted, since this is how we create a mount
 * that shares events with another mount.  If you add a new MNT_*
 * flag, consider how it interacts with shared mounts.
 */
#define MNT_SHARED_MASK	(MNT_UNBINDABLE)
#define MNT_PROPAGATION_MASK	(MNT_SHARED | MNT_UNBINDABLE)


#define MNT_INTERNAL	0x4000

#define MNT_LOCK_READONLY	0x400000

struct vfsmount {
	struct dentry *mnt_root;	/* root of the mounted tree */
	struct super_block *mnt_sb;	/* pointer to superblock */
	int mnt_flags;
};

struct file; /* forward dec */

extern int mnt_want_write(struct vfsmount *mnt);
extern int mnt_want_write_file(struct file *file);
extern int mnt_clone_write(struct vfsmount *mnt);
extern void mnt_drop_write(struct vfsmount *mnt);
extern void mnt_drop_write_file(struct file *file);
extern void mntput(struct vfsmount *mnt);
extern struct vfsmount *mntget(struct vfsmount *mnt);
extern void mnt_pin(struct vfsmount *mnt);
extern void mnt_unpin(struct vfsmount *mnt);
extern int __mnt_is_readonly(struct vfsmount *mnt);

struct file_system_type;
extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
				      int flags, const char *name,
				      void *data);

extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
extern void mark_mounts_for_expiry(struct list_head *mounts);

extern dev_t name_to_dev_t(char *name);

#endif /* _LINUX_MOUNT_H */
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