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[PATCH] msync(MS_SYNC): don't hold mmap_sem while syncing

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It seems bad to hold mmap_sem while performing synchronous disk I/O.  Alter
the msync(MS_SYNC) code so that the lock is released while we sync the file.

Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Andrew Morton 2006-03-24 03:18:13 -08:00 committed by Linus Torvalds
parent 9c50823eeb
commit 707c21c848
1 changed files with 26 additions and 23 deletions
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49
mm/msync.c
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@ -132,35 +132,14 @@ static int msync_interval(struct vm_area_struct *vma, unsigned long addr,
unsigned long end, int flags,
unsigned long *nr_pages_dirtied)
{
int ret = 0;
struct file *file = vma->vm_file;
if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED))
return -EBUSY;
if (file && (vma->vm_flags & VM_SHARED)) {
if (file && (vma->vm_flags & VM_SHARED))
*nr_pages_dirtied = msync_page_range(vma, addr, end);
if (flags & MS_SYNC) {
struct address_space *mapping = file->f_mapping;
int err;
ret = filemap_fdatawrite(mapping);
if (file->f_op && file->f_op->fsync) {
/*
* We don't take i_mutex here because mmap_sem
* is already held.
*/
err = file->f_op->fsync(file,file->f_dentry,1);
if (err && !ret)
ret = err;
}
err = filemap_fdatawait(mapping);
if (!ret)
ret = err;
}
}
return ret;
return 0;
}
asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
@ -233,6 +212,30 @@ asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
fput(file);
down_read(&current->mm->mmap_sem);
vma = find_vma(current->mm, start);
} else if ((flags & MS_SYNC) && file &&
(vma->vm_flags & VM_SHARED)) {
struct address_space *mapping;
int err;
get_file(file);
up_read(&current->mm->mmap_sem);
mapping = file->f_mapping;
error = filemap_fdatawrite(mapping);
if (file->f_op && file->f_op->fsync) {
mutex_lock(&mapping->host->i_mutex);
err = file->f_op->fsync(file,file->f_dentry,1);
mutex_unlock(&mapping->host->i_mutex);
if (err && !error)
error = err;
}
err = filemap_fdatawait(mapping);
if (err && !error)
error = err;
fput(file);
down_read(&current->mm->mmap_sem);
if (error)
goto out_unlock;
vma = find_vma(current->mm, start);
} else {
vma = vma->vm_next;
}