From: Eric Biggers <[email protected]> Add support for STATX_DIOALIGN to ext4, so that direct I/O alignment restrictions are exposed to userspace in a generic way.
Signed-off-by: Eric Biggers <[email protected]> --- fs/ext4/ext4.h | 1 + fs/ext4/file.c | 42 ++++++++++++++++++++++++++---------------- fs/ext4/inode.c | 36 ++++++++++++++++++++++++++++++++++++ 3 files changed, 63 insertions(+), 16 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 75b8d81b24692c..68e964394e9173 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -2968,6 +2968,7 @@ extern struct inode *__ext4_iget(struct super_block *sb, unsigned long ino, extern int ext4_write_inode(struct inode *, struct writeback_control *); extern int ext4_setattr(struct user_namespace *, struct dentry *, struct iattr *); +extern u32 ext4_dio_alignment(struct inode *inode); extern int ext4_getattr(struct user_namespace *, const struct path *, struct kstat *, u32, unsigned int); extern void ext4_evict_inode(struct inode *); diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 26d7426208970d..8bb1c35fd6dd5a 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -36,24 +36,34 @@ #include "acl.h" #include "truncate.h" -static bool ext4_dio_supported(struct kiocb *iocb, struct iov_iter *iter) +/* + * Returns %true if the given DIO request should be attempted with DIO, or + * %false if it should fall back to buffered I/O. + * + * DIO isn't well specified; when it's unsupported (either due to the request + * being misaligned, or due to the file not supporting DIO at all), filesystems + * either fall back to buffered I/O or return EINVAL. For files that don't use + * any special features like encryption or verity, ext4 has traditionally + * returned EINVAL for misaligned DIO. iomap_dio_rw() uses this convention too. + * In this case, we should attempt the DIO, *not* fall back to buffered I/O. + * + * In contrast, in cases where DIO is unsupported due to ext4 features, ext4 + * traditionally falls back to buffered I/O. + * + * This function implements the traditional ext4 behavior in all these cases. + */ +static bool ext4_should_use_dio(struct kiocb *iocb, struct iov_iter *iter) { struct inode *inode = file_inode(iocb->ki_filp); + u32 dio_align = ext4_dio_alignment(inode); - if (IS_ENCRYPTED(inode)) { - if (!fscrypt_dio_supported(inode)) - return false; - if (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), - i_blocksize(inode))) - return false; - } - if (fsverity_active(inode)) + if (dio_align == 0) return false; - if (ext4_should_journal_data(inode)) - return false; - if (ext4_has_inline_data(inode)) - return false; - return true; + + if (dio_align == 1) + return true; + + return IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), dio_align); } static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to) @@ -68,7 +78,7 @@ static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to) inode_lock_shared(inode); } - if (!ext4_dio_supported(iocb, to)) { + if (!ext4_should_use_dio(iocb, to)) { inode_unlock_shared(inode); /* * Fallback to buffered I/O if the operation being performed on @@ -516,7 +526,7 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from) } /* Fallback to buffered I/O if the inode does not support direct I/O. */ - if (!ext4_dio_supported(iocb, from)) { + if (!ext4_should_use_dio(iocb, from)) { if (ilock_shared) inode_unlock_shared(inode); else diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 84c0eb55071d65..75dd332e9da57b 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5536,6 +5536,22 @@ int ext4_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, return error; } +u32 ext4_dio_alignment(struct inode *inode) +{ + if (fsverity_active(inode)) + return 0; + if (ext4_should_journal_data(inode)) + return 0; + if (ext4_has_inline_data(inode)) + return 0; + if (IS_ENCRYPTED(inode)) { + if (!fscrypt_dio_supported(inode)) + return 0; + return i_blocksize(inode); + } + return 1; /* use the iomap defaults */ +} + int ext4_getattr(struct user_namespace *mnt_userns, const struct path *path, struct kstat *stat, u32 request_mask, unsigned int query_flags) { @@ -5551,6 +5567,26 @@ int ext4_getattr(struct user_namespace *mnt_userns, const struct path *path, stat->btime.tv_nsec = ei->i_crtime.tv_nsec; } + /* + * Return the DIO alignment restrictions if requested. We only return + * this information when requested, since on encrypted files it might + * take a fair bit of work to get if the file wasn't opened recently. + */ + if ((request_mask & STATX_DIOALIGN) && S_ISREG(inode->i_mode)) { + u32 dio_align = ext4_dio_alignment(inode); + unsigned int lbs = bdev_logical_block_size(inode->i_sb->s_bdev); + + stat->result_mask |= STATX_DIOALIGN; + if (dio_align == 1) { + /* iomap defaults */ + stat->dio_mem_align = lbs; + stat->dio_offset_align = lbs; + } else { + stat->dio_mem_align = dio_align; + stat->dio_offset_align = dio_align; + } + } + flags = ei->i_flags & EXT4_FL_USER_VISIBLE; if (flags & EXT4_APPEND_FL) stat->attributes |= STATX_ATTR_APPEND; -- 2.37.0 _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
