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| author | Christoph Hellwig <hch@infradead.org> | 2011-06-24 14:29:43 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2011-07-20 20:47:46 -0400 |
| commit | bd5fe6c5eb9c548d7f07fe8f89a150bb6705e8e3 (patch) | |
| tree | ef5341c7747f809aec7ae233f6e3ef90af39be5f /fs/reiserfs | |
| parent | f9b5570d7fdedff32a2e78102bfb54cd1b12b289 (diff) | |
| download | linux-bd5fe6c5eb9c548d7f07fe8f89a150bb6705e8e3.tar.bz2 | |
fs: kill i_alloc_sem
i_alloc_sem is a rather special rw_semaphore. It's the last one that may
be released by a non-owner, and it's write side is always mirrored by
real exclusion. It's intended use it to wait for all pending direct I/O
requests to finish before starting a truncate.
Replace it with a hand-grown construct:
- exclusion for truncates is already guaranteed by i_mutex, so it can
simply fall way
- the reader side is replaced by an i_dio_count member in struct inode
that counts the number of pending direct I/O requests. Truncate can't
proceed as long as it's non-zero
- when i_dio_count reaches non-zero we wake up a pending truncate using
wake_up_bit on a new bit in i_flags
- new references to i_dio_count can't appear while we are waiting for
it to read zero because the direct I/O count always needs i_mutex
(or an equivalent like XFS's i_iolock) for starting a new operation.
This scheme is much simpler, and saves the space of a spinlock_t and a
struct list_head in struct inode (typically 160 bits on a non-debug 64-bit
system).
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/reiserfs')
| -rw-r--r-- | fs/reiserfs/xattr.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c index 4ea2ab41fdee..6938d8c68d6e 100644 --- a/fs/reiserfs/xattr.c +++ b/fs/reiserfs/xattr.c @@ -555,11 +555,10 @@ reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th, reiserfs_write_unlock(inode->i_sb); mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_XATTR); - down_write(&dentry->d_inode->i_alloc_sem); + inode_dio_wait(dentry->d_inode); reiserfs_write_lock(inode->i_sb); err = reiserfs_setattr(dentry, &newattrs); - up_write(&dentry->d_inode->i_alloc_sem); mutex_unlock(&dentry->d_inode->i_mutex); } else update_ctime(inode); |