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
endian.h
/*
* linux/fs/befs/endian.h
*
* Copyright (C) 2001 Will Dyson <will_dyson@pobox.com>
*
* Partially based on similar funtions in the sysv driver.
*/
#ifndef LINUX_BEFS_ENDIAN
#define LINUX_BEFS_ENDIAN
#include <asm/byteorder.h>
static inline u64
fs64_to_cpu(const struct super_block *sb, fs64 n)
{
if (BEFS_SB(sb)->byte_order == BEFS_BYTESEX_LE)
return le64_to_cpu((__force __le64)n);
else
return be64_to_cpu((__force __be64)n);
}
static inline fs64
cpu_to_fs64(const struct super_block *sb, u64 n)
{
if (BEFS_SB(sb)->byte_order == BEFS_BYTESEX_LE)
return (__force fs64)cpu_to_le64(n);
else
return (__force fs64)cpu_to_be64(n);
}
static inline u32
fs32_to_cpu(const struct super_block *sb, fs32 n)
{
if (BEFS_SB(sb)->byte_order == BEFS_BYTESEX_LE)
return le32_to_cpu((__force __le32)n);
else
return be32_to_cpu((__force __be32)n);
}
static inline fs32
cpu_to_fs32(const struct super_block *sb, u32 n)
{
if (BEFS_SB(sb)->byte_order == BEFS_BYTESEX_LE)
return (__force fs32)cpu_to_le32(n);
else
return (__force fs32)cpu_to_be32(n);
}
static inline u16
fs16_to_cpu(const struct super_block *sb, fs16 n)
{
if (BEFS_SB(sb)->byte_order == BEFS_BYTESEX_LE)
return le16_to_cpu((__force __le16)n);
else
return be16_to_cpu((__force __be16)n);
}
static inline fs16
cpu_to_fs16(const struct super_block *sb, u16 n)
{
if (BEFS_SB(sb)->byte_order == BEFS_BYTESEX_LE)
return (__force fs16)cpu_to_le16(n);
else
return (__force fs16)cpu_to_be16(n);
}
/* Composite types below here */
static inline befs_block_run
fsrun_to_cpu(const struct super_block *sb, befs_disk_block_run n)
{
befs_block_run run;
if (BEFS_SB(sb)->byte_order == BEFS_BYTESEX_LE) {
run.allocation_group = le32_to_cpu((__force __le32)n.allocation_group);
run.start = le16_to_cpu((__force __le16)n.start);
run.len = le16_to_cpu((__force __le16)n.len);
} else {
run.allocation_group = be32_to_cpu((__force __be32)n.allocation_group);
run.start = be16_to_cpu((__force __be16)n.start);
run.len = be16_to_cpu((__force __be16)n.len);
}
return run;
}
static inline befs_disk_block_run
cpu_to_fsrun(const struct super_block *sb, befs_block_run n)
{
befs_disk_block_run run;
if (BEFS_SB(sb)->byte_order == BEFS_BYTESEX_LE) {
run.allocation_group = cpu_to_le32(n.allocation_group);
run.start = cpu_to_le16(n.start);
run.len = cpu_to_le16(n.len);
} else {
run.allocation_group = cpu_to_be32(n.allocation_group);
run.start = cpu_to_be16(n.start);
run.len = cpu_to_be16(n.len);
}
return run;
}
static inline befs_data_stream
fsds_to_cpu(const struct super_block *sb, befs_disk_data_stream n)
{
befs_data_stream data;
int i;
for (i = 0; i < BEFS_NUM_DIRECT_BLOCKS; ++i)
data.direct[i] = fsrun_to_cpu(sb, n.direct[i]);
data.max_direct_range = fs64_to_cpu(sb, n.max_direct_range);
data.indirect = fsrun_to_cpu(sb, n.indirect);
data.max_indirect_range = fs64_to_cpu(sb, n.max_indirect_range);
data.double_indirect = fsrun_to_cpu(sb, n.double_indirect);
data.max_double_indirect_range = fs64_to_cpu(sb,
n.
max_double_indirect_range);
data.size = fs64_to_cpu(sb, n.size);
return data;
}
#endif //LINUX_BEFS_ENDIAN
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