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Merge git://oss.sgi.com:8090/oss/git/rc-fixes

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* git://oss.sgi.com:8090/oss/git/rc-fixes:
  Fix a direct I/O locking issue revealed by the new mutex code.
This commit is contained in:
Linus Torvalds 2006-03-14 20:50:45 -08:00
commit 0ee10a4423
1 changed files with 12 additions and 9 deletions
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21
fs/direct-io.c
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@ -1155,15 +1155,16 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
* For writes, i_mutex is not held on entry; it is never taken.
*
* DIO_LOCKING (simple locking for regular files)
* For writes we are called under i_mutex and return with i_mutex held, even though
* it is internally dropped.
* For writes we are called under i_mutex and return with i_mutex held, even
* though it is internally dropped.
* For reads, i_mutex is not held on entry, but it is taken and dropped before
* returning.
*
* DIO_OWN_LOCKING (filesystem provides synchronisation and handling of
* uninitialised data, allowing parallel direct readers and writers)
* For writes we are called without i_mutex, return without it, never touch it.
* For reads, i_mutex is held on entry and will be released before returning.
* For reads we are called under i_mutex and return with i_mutex held, even
* though it may be internally dropped.
*
* Additional i_alloc_sem locking requirements described inline below.
*/
@ -1182,7 +1183,8 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
ssize_t retval = -EINVAL;
loff_t end = offset;
struct dio *dio;
int reader_with_isem = (rw == READ && dio_lock_type == DIO_OWN_LOCKING);
int release_i_mutex = 0;
int acquire_i_mutex = 0;
if (rw & WRITE)
current->flags |= PF_SYNCWRITE;
@ -1225,7 +1227,6 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
* writers need to grab i_alloc_sem only (i_mutex is already held)
* For regular files using DIO_OWN_LOCKING,
* neither readers nor writers take any locks here
* (i_mutex is already held and release for writers here)
*/
dio->lock_type = dio_lock_type;
if (dio_lock_type != DIO_NO_LOCKING) {
@ -1236,7 +1237,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
mapping = iocb->ki_filp->f_mapping;
if (dio_lock_type != DIO_OWN_LOCKING) {
mutex_lock(&inode->i_mutex);
reader_with_isem = 1;
release_i_mutex = 1;
}
retval = filemap_write_and_wait_range(mapping, offset,
@ -1248,7 +1249,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
if (dio_lock_type == DIO_OWN_LOCKING) {
mutex_unlock(&inode->i_mutex);
reader_with_isem = 0;
acquire_i_mutex = 1;
}
}
@ -1269,11 +1270,13 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
nr_segs, blkbits, get_blocks, end_io, dio);
if (rw == READ && dio_lock_type == DIO_LOCKING)
reader_with_isem = 0;
release_i_mutex = 0;
out:
if (reader_with_isem)
if (release_i_mutex)
mutex_unlock(&inode->i_mutex);
else if (acquire_i_mutex)
mutex_lock(&inode->i_mutex);
if (rw & WRITE)
current->flags &= ~PF_SYNCWRITE;
return retval;