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fuse: fix race in llseek

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Fuse doesn't use i_mutex to protect setting i_size, and so
generic_file_llseek() can be racy: it doesn't use i_size_read().

So do a fuse specific llseek method, which does use i_size_read().

[akpm@linux-foundation.org: make `retval' loff_t]
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Miklos Szeredi 2008-04-30 00:54:45 -07:00 committed by Linus Torvalds
parent b48badf013
commit 5559b8f4d1
1 changed files with 27 additions and 2 deletions
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29
fs/fuse/file.c
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@ -1431,8 +1431,33 @@ static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
return err ? 0 : outarg.block; return err ? 0 : outarg.block;
} }
static loff_t fuse_file_llseek(struct file *file, loff_t offset, int origin)
{
loff_t retval;
struct inode *inode = file->f_path.dentry->d_inode;
mutex_lock(&inode->i_mutex);
switch (origin) {
case SEEK_END:
offset += i_size_read(inode);
break;
case SEEK_CUR:
offset += file->f_pos;
}
retval = -EINVAL;
if (offset >= 0 && offset <= inode->i_sb->s_maxbytes) {
if (offset != file->f_pos) {
file->f_pos = offset;
file->f_version = 0;
}
retval = offset;
}
mutex_unlock(&inode->i_mutex);
return retval;
}
static const struct file_operations fuse_file_operations = { static const struct file_operations fuse_file_operations = {
.llseek = generic_file_llseek, .llseek = fuse_file_llseek,
.read = do_sync_read, .read = do_sync_read,
.aio_read = fuse_file_aio_read, .aio_read = fuse_file_aio_read,
.write = do_sync_write, .write = do_sync_write,
@ -1448,7 +1473,7 @@ static const struct file_operations fuse_file_operations = {
}; };
static const struct file_operations fuse_direct_io_file_operations = { static const struct file_operations fuse_direct_io_file_operations = {
.llseek = generic_file_llseek, .llseek = fuse_file_llseek,
.read = fuse_direct_read, .read = fuse_direct_read,
.write = fuse_direct_write, .write = fuse_direct_write,
.open = fuse_open, .open = fuse_open,