[PATCH 23/23] vfs: Teach readahead to use the file_hotplug_lock

Eric W. Biederman
2009-06-03T18:17:44Z

From: Eric W. Biederman <ebiederm@maxwell.aristanetworks.com>

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
---
mm/filemap.c | 25 ++++++++++++++++---------
1 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 379ff0b..5016aa5 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1402,16 +1402,23 @@ SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count)

ret = -EBADF;
file = fget(fd);
- if (file) {
- if (file->f_mode & FMODE_READ) {
- struct address_space *mapping = file->f_mapping;
- pgoff_t start = offset >> PAGE_CACHE_SHIFT;
- pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
- unsigned long len = end - start + 1;
- ret = do_readahead(mapping, file, start, len);
- }
- fput(file);
+ if (!file)
+ goto out;
+
+ if (!(file->f_mode & FMODE_READ))
+ goto out_fput;
+
+ if (file_hotplug_read_trylock(file)) {
+ struct address_space *mapping = file->f_mapping;
+ pgoff_t start = offset >> PAGE_CACHE_SHIFT;
+ pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
+ unsigned long len = end - start + 1;
+ ret = do_readahead(mapping, file, start, len);
+ file_hotplug_read_unlock(file);
}
+out_fput:
+ fput(file);
+out:
return ret;
}
#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
--
1.6.3.1.54.g99dd.dirty