https://github.com/torvalds/linux
Revision 914ee295af418e936ec20a08c1663eaabe4cd07a authored by Xin Zhong on 09 December 2010, 09:30:14 UTC, committed by Chris Mason on 10 December 2010, 21:29:10 UTC
This problem is found in meego testing: http://bugs.meego.com/show_bug.cgi?id=6672 A file in btrfs is mmaped and the mmaped buffer is passed to pwrite to write to the same page of the same file. In btrfs_file_aio_write(), the pages is locked by prepare_pages(). So when btrfs_copy_from_user() is called, page fault happens and the same page needs to be locked again in filemap_fault(). The fix is to move iov_iter_fault_in_readable() before prepage_pages() to make page fault happen before pages are locked. And also disable page fault in critical region in btrfs_copy_from_user(). Reviewed-by: Yan, Zheng<zheng.z.yan@intel.com> Signed-off-by: Zhong, Xin <xin.zhong@intel.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
1 parent f106e82
Tip revision: 914ee295af418e936ec20a08c1663eaabe4cd07a authored by Xin Zhong on 09 December 2010, 09:30:14 UTC
Btrfs: pwrite blocked when writing from the mmaped buffer of the same page
Btrfs: pwrite blocked when writing from the mmaped buffer of the same page
Tip revision: 914ee29
befs.h
/*
* befs.h
*
* Copyright (C) 2001-2002 Will Dyson <will_dyson@pobox.com>
* Copyright (C) 1999 Makoto Kato (m_kato@ga2.so-net.ne.jp)
*/
#ifndef _LINUX_BEFS_H
#define _LINUX_BEFS_H
#include "befs_fs_types.h"
/* used in debug.c */
#define BEFS_VERSION "0.9.3"
typedef u64 befs_blocknr_t;
/*
* BeFS in memory structures
*/
typedef struct befs_mount_options {
gid_t gid;
uid_t uid;
int use_gid;
int use_uid;
int debug;
char *iocharset;
} befs_mount_options;
typedef struct befs_sb_info {
u32 magic1;
u32 block_size;
u32 block_shift;
int byte_order;
befs_off_t num_blocks;
befs_off_t used_blocks;
u32 inode_size;
u32 magic2;
/* Allocation group information */
u32 blocks_per_ag;
u32 ag_shift;
u32 num_ags;
/* jornal log entry */
befs_block_run log_blocks;
befs_off_t log_start;
befs_off_t log_end;
befs_inode_addr root_dir;
befs_inode_addr indices;
u32 magic3;
befs_mount_options mount_opts;
struct nls_table *nls;
} befs_sb_info;
typedef struct befs_inode_info {
u32 i_flags;
u32 i_type;
befs_inode_addr i_inode_num;
befs_inode_addr i_parent;
befs_inode_addr i_attribute;
union {
befs_data_stream ds;
char symlink[BEFS_SYMLINK_LEN];
} i_data;
struct inode vfs_inode;
} befs_inode_info;
enum befs_err {
BEFS_OK,
BEFS_ERR,
BEFS_BAD_INODE,
BEFS_BT_END,
BEFS_BT_EMPTY,
BEFS_BT_MATCH,
BEFS_BT_PARMATCH,
BEFS_BT_NOT_FOUND
};
/****************************/
/* debug.c */
void befs_error(const struct super_block *sb, const char *fmt, ...);
void befs_warning(const struct super_block *sb, const char *fmt, ...);
void befs_debug(const struct super_block *sb, const char *fmt, ...);
void befs_dump_super_block(const struct super_block *sb, befs_super_block *);
void befs_dump_inode(const struct super_block *sb, befs_inode *);
void befs_dump_index_entry(const struct super_block *sb, befs_disk_btree_super *);
void befs_dump_index_node(const struct super_block *sb, befs_btree_nodehead *);
/****************************/
/* Gets a pointer to the private portion of the super_block
* structure from the public part
*/
static inline befs_sb_info *
BEFS_SB(const struct super_block *super)
{
return (befs_sb_info *) super->s_fs_info;
}
static inline befs_inode_info *
BEFS_I(const struct inode *inode)
{
return list_entry(inode, struct befs_inode_info, vfs_inode);
}
static inline befs_blocknr_t
iaddr2blockno(struct super_block *sb, befs_inode_addr * iaddr)
{
return ((iaddr->allocation_group << BEFS_SB(sb)->ag_shift) +
iaddr->start);
}
static inline befs_inode_addr
blockno2iaddr(struct super_block *sb, befs_blocknr_t blockno)
{
befs_inode_addr iaddr;
iaddr.allocation_group = blockno >> BEFS_SB(sb)->ag_shift;
iaddr.start =
blockno - (iaddr.allocation_group << BEFS_SB(sb)->ag_shift);
iaddr.len = 1;
return iaddr;
}
static inline unsigned int
befs_iaddrs_per_block(struct super_block *sb)
{
return BEFS_SB(sb)->block_size / sizeof (befs_disk_inode_addr);
}
static inline int
befs_iaddr_is_empty(befs_inode_addr * iaddr)
{
return (!iaddr->allocation_group) && (!iaddr->start) && (!iaddr->len);
}
static inline size_t
befs_brun_size(struct super_block *sb, befs_block_run run)
{
return BEFS_SB(sb)->block_size * run.len;
}
#include "endian.h"
#endif /* _LINUX_BEFS_H */
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