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fuse: create helper function if DIO write needs exclusive lock

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This makes the code a bit easier to read and allows to more easily add more
conditions when an exclusive lock is needed.

Signed-off-by: Bernd Schubert <bschubert@ddn.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Bernd Schubert 2023-08-22 21:48:18 +02:00 committed by Miklos Szeredi
parent 9511176bba
commit 699cf8246e
1 changed files with 45 additions and 18 deletions
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63
fs/fuse/file.c
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@ -1299,6 +1299,47 @@ static ssize_t fuse_perform_write(struct kiocb *iocb, struct iov_iter *ii)
return res;
}
static bool fuse_io_past_eof(struct kiocb *iocb, struct iov_iter *iter)
{
struct inode *inode = file_inode(iocb->ki_filp);
return iocb->ki_pos + iov_iter_count(iter) > i_size_read(inode);
}
/*
* @return true if an exclusive lock for direct IO writes is needed
*/
static bool fuse_dio_wr_exclusive_lock(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct fuse_file *ff = file->private_data;
struct inode *inode = file_inode(iocb->ki_filp);
/* Server side has to advise that it supports parallel dio writes. */
if (!(ff->open_flags & FOPEN_PARALLEL_DIRECT_WRITES))
return true;
/*
* Append will need to know the eventual EOF - always needs an
* exclusive lock.
*/
if (iocb->ki_flags & IOCB_APPEND)
return true;
/*
* Combination of page access and direct-io is difficult, shared locks
* actually introduce a conflict.
*/
if (get_fuse_conn(inode)->direct_io_allow_mmap)
return true;
/* Parallel dio beyond EOF is not supported, at least for now. */
if (fuse_io_past_eof(iocb, from))
return true;
return false;
}
static ssize_t fuse_cache_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
@ -1558,26 +1599,12 @@ static ssize_t fuse_direct_read_iter(struct kiocb *iocb, struct iov_iter *to)
return res;
}
static bool fuse_direct_write_extending_i_size(struct kiocb *iocb,
struct iov_iter *iter)
{
struct inode *inode = file_inode(iocb->ki_filp);
return iocb->ki_pos + iov_iter_count(iter) > i_size_read(inode);
}
static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct inode *inode = file_inode(iocb->ki_filp);
struct file *file = iocb->ki_filp;
struct fuse_file *ff = file->private_data;
struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);
ssize_t res;
bool exclusive_lock =
!(ff->open_flags & FOPEN_PARALLEL_DIRECT_WRITES) ||
get_fuse_conn(inode)->direct_io_allow_mmap ||
iocb->ki_flags & IOCB_APPEND ||
fuse_direct_write_extending_i_size(iocb, from);
bool exclusive_lock = fuse_dio_wr_exclusive_lock(iocb, from);
/*
* Take exclusive lock if
@ -1591,10 +1618,10 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
else {
inode_lock_shared(inode);
/* A race with truncate might have come up as the decision for
* the lock type was done without holding the lock, check again.
/*
* Previous check was without any lock and might have raced.
*/
if (fuse_direct_write_extending_i_size(iocb, from)) {
if (fuse_io_past_eof(iocb, from)) {
inode_unlock_shared(inode);
inode_lock(inode);
exclusive_lock = true;