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authorMaxim Patlasov <MPatlasov@parallels.com>2013-09-13 19:20:16 +0400
committerMiklos Szeredi <mszeredi@suse.cz>2013-09-18 14:19:59 +0200
commit0ab08f576b9e6a6b689fc6b4e632079b978e619b (patch)
tree5256bdda3a818970473c71b33f14bd8564708e14 /fs/fuse
parentbde52788bdb755b9e4b75db6c434f30e32a0ca0b (diff)
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fuse: fix fallocate vs. ftruncate race
A former patch introducing FUSE_I_SIZE_UNSTABLE flag provided detailed description of races between ftruncate and anyone who can extend i_size: > 1. As in the previous scenario fuse_dentry_revalidate() discovered that i_size > changed (due to our own fuse_do_setattr()) and is going to call > truncate_pagecache() for some 'new_size' it believes valid right now. But by > the time that particular truncate_pagecache() is called ... > 2. fuse_do_setattr() returns (either having called truncate_pagecache() or > not -- it doesn't matter). > 3. The file is extended either by write(2) or ftruncate(2) or fallocate(2). > 4. mmap-ed write makes a page in the extended region dirty. This patch adds necessary bits to fuse_file_fallocate() to protect from that race. Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/fuse')
-rw-r--r--fs/fuse/file.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index f9f07c4..4598345 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2467,6 +2467,7 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
{
struct fuse_file *ff = file->private_data;
struct inode *inode = file->f_inode;
+ struct fuse_inode *fi = get_fuse_inode(inode);
struct fuse_conn *fc = ff->fc;
struct fuse_req *req;
struct fuse_fallocate_in inarg = {
@@ -2495,6 +2496,9 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
}
}
+ if (!(mode & FALLOC_FL_KEEP_SIZE))
+ set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
+
req = fuse_get_req_nopages(fc);
if (IS_ERR(req)) {
err = PTR_ERR(req);
@@ -2527,6 +2531,9 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
fuse_invalidate_attr(inode);
out:
+ if (!(mode & FALLOC_FL_KEEP_SIZE))
+ clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
+
if (lock_inode)
mutex_unlock(&inode->i_mutex);