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| author | Christoph Hellwig <hch@lst.de> | 2024-08-27 08:50:47 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-08-28 16:53:57 +0200 |
| commit | 57413d8e172c10c90fbd91f98d0f7d8eb27e824c (patch) | |
| tree | 85ee8b00d68a0adf810bd4cdc04009c6f8042684 /fs/open.c | |
| parent | ext4: remove tracing for FALLOC_FL_NO_HIDE_STALE (diff) | |
| download | linux-57413d8e172c10c90fbd91f98d0f7d8eb27e824c.tar.xz linux-57413d8e172c10c90fbd91f98d0f7d8eb27e824c.zip | |
fs: sort out the fallocate mode vs flag mess
The fallocate system call takes a mode argument, but that argument
contains a wild mix of exclusive modes and an optional flags.
Replace FALLOC_FL_SUPPORTED_MASK with FALLOC_FL_MODE_MASK, which excludes
the optional flag bit, so that we can use switch statement on the value
to easily enumerate the cases while getting the check for duplicate modes
for free.
To make this (and in the future the file system implementations) more
readable also add a symbolic name for the 0 mode used to allocate blocks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240827065123.1762168-4-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'fs/open.c')
| -rw-r--r-- | fs/open.c | 51 |
1 files changed, 25 insertions, 26 deletions
diff --git a/fs/open.c b/fs/open.c index 22adbef7ecc2..daf1b55ca818 100644 --- a/fs/open.c +++ b/fs/open.c @@ -252,40 +252,39 @@ int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len) if (offset < 0 || len <= 0) return -EINVAL; - /* Return error if mode is not supported */ - if (mode & ~FALLOC_FL_SUPPORTED_MASK) + if (mode & ~(FALLOC_FL_MODE_MASK | FALLOC_FL_KEEP_SIZE)) return -EOPNOTSUPP; - /* Punch hole and zero range are mutually exclusive */ - if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) == - (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) - return -EOPNOTSUPP; - - /* Punch hole must have keep size set */ - if ((mode & FALLOC_FL_PUNCH_HOLE) && - !(mode & FALLOC_FL_KEEP_SIZE)) + /* + * Modes are exclusive, even if that is not obvious from the encoding + * as bit masks and the mix with the flag in the same namespace. + * + * To make things even more complicated, FALLOC_FL_ALLOCATE_RANGE is + * encoded as no bit set. + */ + switch (mode & FALLOC_FL_MODE_MASK) { + case FALLOC_FL_ALLOCATE_RANGE: + case FALLOC_FL_UNSHARE_RANGE: + case FALLOC_FL_ZERO_RANGE: + break; + case FALLOC_FL_PUNCH_HOLE: + if (!(mode & FALLOC_FL_KEEP_SIZE)) + return -EOPNOTSUPP; + break; + case FALLOC_FL_COLLAPSE_RANGE: + case FALLOC_FL_INSERT_RANGE: + if (mode & FALLOC_FL_KEEP_SIZE) + return -EOPNOTSUPP; + break; + default: return -EOPNOTSUPP; - - /* Collapse range should only be used exclusively. */ - if ((mode & FALLOC_FL_COLLAPSE_RANGE) && - (mode & ~FALLOC_FL_COLLAPSE_RANGE)) - return -EINVAL; - - /* Insert range should only be used exclusively. */ - if ((mode & FALLOC_FL_INSERT_RANGE) && - (mode & ~FALLOC_FL_INSERT_RANGE)) - return -EINVAL; - - /* Unshare range should only be used with allocate mode. */ - if ((mode & FALLOC_FL_UNSHARE_RANGE) && - (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE))) - return -EINVAL; + } if (!(file->f_mode & FMODE_WRITE)) return -EBADF; /* - * We can only allow pure fallocate on append only files + * On append-only files only space preallocation is supported. */ if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode)) return -EPERM; |