* [PATCH v2 1/4] minix: add iomap infrastructure
2026-06-28 5:15 [PATCH v2 0/4] minix: convert to iomap and add direct I/O Jeremy Bingham
@ 2026-06-28 5:15 ` Jeremy Bingham
2026-06-28 5:15 ` [PATCH v2 2/4] minix: convert address space operations to iomap Jeremy Bingham
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Jeremy Bingham @ 2026-06-28 5:15 UTC (permalink / raw)
To: linux-fsdevel
Cc: linux-kernel, brauner, jkoolstra, jack, hch, viro, syzkaller,
Jeremy Bingham
Add an iomap implementation for minix, adapted from the out-of-tree
xiafs module's iomap code. The xiafs module, in turn, borrowed heavily
from minix's own code.
The iomap_begin function replaces get_block for the iomap path:
it walks the indirect block tree, allocates blocks when needed, and
returns the mapping in a struct iomap. The iomap_end function is a
nop since minix has no extents or transactions to finalize.
Because minix has two filesystem versions (V1 with 16-bit block
numbers, V2/V3 with 32-bit) that share itree_common.c via #include,
the iomap.c file follows the same pattern. It is #included into
itree_v1.c and itree_v2.c so it can use the version-specific block_t,
block_to_cpu, and cpu_to_block definitions directly.
Each version gets its own iomap_ops struct (V1_minix_iomap_ops,
V2_minix_iomap_ops) with thin wrappers around the shared
minix_iomap_begin/minix_iomap_end. A minix_iomap_ops_ver() helper
selects the correct ops based on the filesystem version.
minix_get_block is exported from inode.c for use by the iomap
writeback path and the directory aops that still use buffer_heads.
Signed-off-by: Jeremy Bingham <jbingham@gmail.com>
---
fs/minix/iomap.c | 114 ++++++++++++++++++++++++++++++++++++++++++++
fs/minix/itree_v1.c | 25 +++++++++-
fs/minix/itree_v2.c | 17 ++++++-
fs/minix/minix.h | 23 ++++++++-
4 files changed, 175 insertions(+), 4 deletions(-)
create mode 100644 fs/minix/iomap.c
diff --git a/fs/minix/iomap.c b/fs/minix/iomap.c
new file mode 100644
index 000000000000..7bb0439e3669
--- /dev/null
+++ b/fs/minix/iomap.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * iomap functions for minix. At least the first pass of this file was taken
+ * from the xiafs iomap.c, which is fitting since the xiafs module in turn
+ * borrowed heavily from the modernized minix fs kernel module.
+ */
+
+/*
+ * minix_iomap_begin - map a file range to disk blocks. It acts as a replacement
+ * for get_block in itree_common.c, at least in the important ways, and is
+ * adapted from it, but it uses iomap instead of buffer_head. This is taken
+ * directly from the out-of-tree xiafs iomap changes, and the exfat iomap
+ * changes were an inspiration for that.
+ */
+static int minix_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
+ unsigned int flags, struct iomap *iomap, struct iomap *srcmap)
+{
+ struct super_block *sb = inode->i_sb;
+ unsigned int blkbits = sb->s_blocksize_bits;
+ sector_t iblock = offset >> blkbits;
+ int create = flags & IOMAP_WRITE;
+
+ /* Mostly taken from modern-xiafs itree.c get_block with elements from
+ * similar exfat operations.
+ */
+ int offsets[DEPTH];
+ Indirect chain[DEPTH];
+ Indirect *partial;
+ int depth = block_to_path(inode, iblock, offsets);
+ int left;
+ int err = -EIO;
+
+ sector_t phys;
+
+ /* block is beyond max file size */
+ if (depth == 0)
+ goto out;
+
+ iomap->bdev = inode->i_sb->s_bdev;
+
+reread:
+ partial = get_branch(inode, depth, offsets, chain, &err);
+
+ /* Simplest case - block found, no allocation needed */
+ if (!partial) {
+ /* Bit of a weird order, but it'll make sense when you get to
+ * the bottom.
+ */
+ iomap->flags = IOMAP_F_MERGED;
+got_it:
+ phys = block_to_cpu(chain[depth - 1].key);
+ partial = chain+depth-1;
+ /* Set up the iomap struct before cleaning up */
+ iomap->type = IOMAP_MAPPED;
+ iomap->addr = (u64)phys << blkbits;
+ iomap->length = 1 << blkbits;
+ iomap->offset = (u64)iblock << blkbits;
+ goto cleanup;
+ }
+
+ /* Next simple case - plain lookup or failed read of indirect block */
+ if (!create || err == -EIO) {
+ iomap->type = IOMAP_HOLE;
+ iomap->addr = IOMAP_NULL_ADDR;
+ iomap->length = 1 << blkbits;
+ iomap->offset = (u64)iblock << blkbits;
+ iomap->flags = 0;
+cleanup:
+ while (partial > chain) {
+ brelse(partial->bh);
+ partial--;
+ }
+out:
+ return err;
+ }
+
+ /*
+ * Indirect block might be removed by truncate while we were
+ * reading it. Handling of that case (forget what we've got and
+ * reread) is taken out of the main path.
+ */
+ if (err == -EAGAIN)
+ goto changed;
+
+ left = (chain + depth) - partial;
+ err = alloc_branch(inode, left, offsets + (partial - chain), partial);
+ if (err)
+ goto cleanup;
+
+ if (splice_branch(inode, chain, partial, left) < 0)
+ goto changed;
+
+ /* Successful allocation, mapping it. */
+ iomap->flags = IOMAP_F_NEW;
+ goto got_it;
+
+changed:
+ while (partial > chain) {
+ brelse(partial->bh);
+ partial--;
+ }
+ goto reread;
+}
+
+/*
+ * minix_iomap_end ends up being a nop; since minix doesn't have any extents or
+ * transactions to worry about, there isn't anything to update here. The on-disk
+ * indirect blocks get dirtied in minix_iomap_begin.
+ */
+static int minix_iomap_end(struct inode *inode, loff_t offset, loff_t length,
+ ssize_t written, unsigned int flags, struct iomap *iomap)
+{
+ return 0;
+}
diff --git a/fs/minix/itree_v1.c b/fs/minix/itree_v1.c
index 1fed906042aa..58c29f4443d3 100644
--- a/fs/minix/itree_v1.c
+++ b/fs/minix/itree_v1.c
@@ -49,6 +49,18 @@ static int block_to_path(struct inode * inode, long block, int offsets[DEPTH])
}
#include "itree_common.c"
+/* NOTA BENE:
+ *
+ * This is icky to me, but at the same time having it be a standalone C file
+ * that's compiled to object form and linked separately like it is in xiafs is
+ * much nastier in minix because of the different versions of the minix fs that
+ * have some very, very different aspects, like the size of block_t. I don't
+ * like it, but since minix already has this pattern where a common itree file
+ * is included in the itree_v1 and itree_v2(and v3) files, I'm including iomap.c
+ * in these files as well. It does at least avoid exporting some currently
+ * static functions that aren't needed anywhere but itree_common.c and iomap.c.
+ */
+#include "iomap.c"
int V1_minix_get_block(struct inode * inode, long block,
struct buffer_head *bh_result, int create)
@@ -61,7 +73,18 @@ void V1_minix_truncate(struct inode * inode)
truncate(inode);
}
-unsigned V1_minix_blocks(loff_t size, struct super_block *sb)
+unsigned int V1_minix_blocks(loff_t size, struct super_block *sb)
{
return nblocks(size, sb);
}
+
+int V1_minix_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
+ unsigned int flags, struct iomap *iomap, struct iomap *srcmap)
+{
+ return minix_iomap_begin(inode, offset, length, flags, iomap, srcmap);
+}
+
+const struct iomap_ops V1_minix_iomap_ops = {
+ .iomap_begin = V1_minix_iomap_begin,
+ .iomap_end = minix_iomap_end,
+};
diff --git a/fs/minix/itree_v2.c b/fs/minix/itree_v2.c
index 9d00f31a2d9d..fc7a5ae8fa1c 100644
--- a/fs/minix/itree_v2.c
+++ b/fs/minix/itree_v2.c
@@ -57,6 +57,10 @@ static int block_to_path(struct inode * inode, long block, int offsets[DEPTH])
}
#include "itree_common.c"
+/* See the note in itree_v1 in a comment that starts "NOTA BENE" for an
+ * explanation for why iomap.c is included here.
+ */
+#include "iomap.c"
int V2_minix_get_block(struct inode * inode, long block,
struct buffer_head *bh_result, int create)
@@ -69,7 +73,18 @@ void V2_minix_truncate(struct inode * inode)
truncate(inode);
}
-unsigned V2_minix_blocks(loff_t size, struct super_block *sb)
+unsigned int V2_minix_blocks(loff_t size, struct super_block *sb)
{
return nblocks(size, sb);
}
+
+int V2_minix_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
+ unsigned int flags, struct iomap *iomap, struct iomap *srcmap)
+{
+ return minix_iomap_begin(inode, offset, length, flags, iomap, srcmap);
+}
+
+const struct iomap_ops V2_minix_iomap_ops = {
+ .iomap_begin = V2_minix_iomap_begin,
+ .iomap_end = minix_iomap_end,
+};
diff --git a/fs/minix/minix.h b/fs/minix/minix.h
index f2025c9b5825..77e503cca97f 100644
--- a/fs/minix/minix.h
+++ b/fs/minix/minix.h
@@ -5,6 +5,7 @@
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/minix_fs.h>
+#include <linux/iomap.h>
#define INODE_VERSION(inode) minix_sb(inode->i_sb)->s_version
#define MINIX_V1 0x0001 /* original minix fs */
@@ -69,6 +70,8 @@ extern int V1_minix_get_block(struct inode *, long, struct buffer_head *, int);
extern int V2_minix_get_block(struct inode *, long, struct buffer_head *, int);
extern unsigned V1_minix_blocks(loff_t, struct super_block *);
extern unsigned V2_minix_blocks(loff_t, struct super_block *);
+extern int minix_get_block(struct inode *inode, sector_t block,
+ struct buffer_head *bh_result, int create);
struct minix_dir_entry *minix_find_entry(struct dentry *, struct folio **);
int minix_add_link(struct dentry*, struct inode*);
@@ -80,10 +83,20 @@ int minix_set_link(struct minix_dir_entry *de, struct folio *folio,
struct minix_dir_entry *minix_dotdot(struct inode*, struct folio **);
ino_t minix_inode_by_name(struct dentry*);
+extern int V1_minix_iomap_begin(struct inode *inode, loff_t offset,
+ loff_t length, unsigned int flags, struct iomap *iomap,
+ struct iomap *srcmap);
+extern int V2_minix_iomap_begin(struct inode *inode, loff_t offset,
+ loff_t length, unsigned int flags, struct iomap *iomap,
+ struct iomap *srcmap);
+
+extern const struct address_space_operations minix_aops;
extern const struct inode_operations minix_file_inode_operations;
extern const struct inode_operations minix_dir_inode_operations;
extern const struct file_operations minix_file_operations;
extern const struct file_operations minix_dir_operations;
+extern const struct iomap_ops V1_minix_iomap_ops;
+extern const struct iomap_ops V2_minix_iomap_ops;
static inline struct minix_sb_info *minix_sb(struct super_block *sb)
{
@@ -95,11 +108,17 @@ static inline struct minix_inode_info *minix_i(struct inode *inode)
return container_of(inode, struct minix_inode_info, vfs_inode);
}
-static inline unsigned minix_blocks_needed(unsigned bits, unsigned blocksize)
+static inline unsigned int minix_blocks_needed(unsigned int bits, unsigned int blocksize)
{
return DIV_ROUND_UP(bits, blocksize * 8);
}
+static inline const struct iomap_ops *minix_iomap_ops_ver(struct inode *inode)
+{
+ return (INODE_VERSION(inode) == MINIX_V1) ?
+ &V1_minix_iomap_ops : &V2_minix_iomap_ops;
+}
+
#if defined(CONFIG_MINIX_FS_NATIVE_ENDIAN) && \
defined(CONFIG_MINIX_FS_BIG_ENDIAN_16BIT_INDEXED)
@@ -129,7 +148,7 @@ static inline unsigned minix_blocks_needed(unsigned bits, unsigned blocksize)
* big-endian 16bit indexed bitmaps
*/
-static inline int minix_find_first_zero_bit(const void *vaddr, unsigned size)
+static inline int minix_find_first_zero_bit(const void *vaddr, unsigned int size)
{
const unsigned short *p = vaddr, *addr = vaddr;
unsigned short num;
--
2.47.3
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v2 2/4] minix: convert address space operations to iomap
2026-06-28 5:15 [PATCH v2 0/4] minix: convert to iomap and add direct I/O Jeremy Bingham
2026-06-28 5:15 ` [PATCH v2 1/4] minix: add iomap infrastructure Jeremy Bingham
@ 2026-06-28 5:15 ` Jeremy Bingham
2026-06-28 5:15 ` [PATCH v2 3/4] minix: convert file operations to iomap and add Jeremy Bingham
2026-06-28 5:15 ` [PATCH v2 4/4] minix: fix symlink and truncate for iomap Jeremy Bingham
3 siblings, 0 replies; 5+ messages in thread
From: Jeremy Bingham @ 2026-06-28 5:15 UTC (permalink / raw)
To: linux-fsdevel
Cc: linux-kernel, brauner, jkoolstra, jack, hch, viro, syzkaller,
Jeremy Bingham
Convert minix regular file and symlink address space operations from
buffer_head to iomap. The new minix_aops uses iomap_dirty_folio,
iomap_invalidate_folio, iomap_bio_read_folio, iomap_bio_readahead,
iomap_writepages, iomap_bmap, and related iomap helpers.
The write_begin/write_end callbacks are removed since buffered writes
now go through iomap_file_buffered_write in file.c.
Directories keep using buffer_heads via a new minix_dir_aops, which
retains the old block_dirty_folio, block_read_full_folio,
block_write_begin, generic_write_end, and mpage_writepages. This is
necessary because directory entry manipulation (minix_prepare_chunk,
minix_write_begin) still uses the buffer_head chunk protocol.
minix_bmap is converted from generic_block_bmap to iomap_bmap.
The minix_get_block function is exported (non-static) so the
directory aops can still use it for block_write_begin and
mpage_writepages.
Signed-off-by: Jeremy Bingham <jbingham@gmail.com>
---
fs/minix/inode.c | 86 +++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 78 insertions(+), 8 deletions(-)
diff --git a/fs/minix/inode.c b/fs/minix/inode.c
index c30cc590698d..2ba6766fce51 100644
--- a/fs/minix/inode.c
+++ b/fs/minix/inode.c
@@ -436,7 +436,32 @@ static int minix_statfs(struct dentry *dentry, struct kstatfs *buf)
return 0;
}
-static int minix_get_block(struct inode *inode, sector_t block,
+static ssize_t minix_writeback_range(struct iomap_writepage_ctx *wpc,
+ struct folio *folio, u64 pos, unsigned int len, u64 end_pos)
+{
+ int error;
+
+ if (pos < wpc->iomap.offset ||
+ pos >= wpc->iomap.offset + wpc->iomap.length) {
+ if (INODE_VERSION(wpc->inode) == MINIX_V1)
+ error = V1_minix_iomap_begin(wpc->inode, pos, len, IOMAP_WRITE,
+ &wpc->iomap, NULL);
+ else
+ error = V2_minix_iomap_begin(wpc->inode, pos, len, IOMAP_WRITE,
+ &wpc->iomap, NULL);
+ if (error)
+ return error;
+ }
+
+ return iomap_add_to_ioend(wpc, folio, pos, end_pos, len);
+}
+
+static const struct iomap_writeback_ops minix_writeback_ops = {
+ .writeback_range = minix_writeback_range,
+ .writeback_submit = iomap_ioend_writeback_submit,
+};
+
+int minix_get_block(struct inode *inode, sector_t block,
struct buffer_head *bh_result, int create)
{
if (INODE_VERSION(inode) == MINIX_V1)
@@ -445,17 +470,45 @@ static int minix_get_block(struct inode *inode, sector_t block,
return V2_minix_get_block(inode, block, bh_result, create);
}
-static int minix_writepages(struct address_space *mapping,
+/* The old minix_writepages, preserved for directory operations. */
+static int minix_block_writepages(struct address_space *mapping,
struct writeback_control *wbc)
{
return mpage_writepages(mapping, wbc, minix_get_block);
}
+static int minix_writepages(struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+ struct iomap_writepage_ctx wpc = {
+ .inode = mapping->host,
+ .wbc = wbc,
+ .ops = &minix_writeback_ops,
+ };
+ return iomap_writepages(&wpc);
+}
+
static int minix_read_folio(struct file *file, struct folio *folio)
+{
+ const struct iomap_ops *ops = minix_iomap_ops_ver(folio->mapping->host);
+
+ iomap_bio_read_folio(folio, ops);
+ return 0;
+}
+
+/* The old minix_read_folio, preserved for directory operations. */
+static int minix_block_read_folio(struct file *file, struct folio *folio)
{
return block_read_full_folio(folio, minix_get_block);
}
+static void minix_readahead(struct readahead_control *rac)
+{
+ const struct iomap_ops *ops = minix_iomap_ops_ver(rac->mapping->host);
+
+ iomap_bio_readahead(rac, ops);
+}
+
int minix_prepare_chunk(struct folio *folio, loff_t pos, unsigned len)
{
return __block_write_begin(folio, pos, len, minix_get_block);
@@ -487,19 +540,36 @@ static int minix_write_begin(const struct kiocb *iocb,
static sector_t minix_bmap(struct address_space *mapping, sector_t block)
{
- return generic_block_bmap(mapping,block,minix_get_block);
+ const struct iomap_ops *ops = minix_iomap_ops_ver(mapping->host);
+
+ return iomap_bmap(mapping, block, ops);
}
-static const struct address_space_operations minix_aops = {
- .dirty_folio = block_dirty_folio,
- .invalidate_folio = block_invalidate_folio,
+const struct address_space_operations minix_aops = {
+ .dirty_folio = iomap_dirty_folio,
+ .invalidate_folio = iomap_invalidate_folio,
.read_folio = minix_read_folio,
+ .readahead = minix_readahead,
.writepages = minix_writepages,
+ .migrate_folio = filemap_migrate_folio,
+ .bmap = minix_bmap,
+ .is_partially_uptodate = iomap_is_partially_uptodate,
+ .release_folio = iomap_release_folio,
+ .error_remove_folio = generic_error_remove_folio,
+};
+
+/* A special aops for directories that keeps using the buffer head chunks, at
+ * least for the time being.
+ */
+static const struct address_space_operations minix_dir_aops = {
+ .dirty_folio = block_dirty_folio,
+ .invalidate_folio = block_invalidate_folio,
+ .read_folio = minix_block_read_folio,
.write_begin = minix_write_begin,
.write_end = generic_write_end,
.migrate_folio = buffer_migrate_folio,
.bmap = minix_bmap,
- .direct_IO = noop_direct_IO
+ .writepages = minix_block_writepages,
};
static const struct inode_operations minix_symlink_inode_operations = {
@@ -516,7 +586,7 @@ void minix_set_inode(struct inode *inode, dev_t rdev)
} else if (S_ISDIR(inode->i_mode)) {
inode->i_op = &minix_dir_inode_operations;
inode->i_fop = &minix_dir_operations;
- inode->i_mapping->a_ops = &minix_aops;
+ inode->i_mapping->a_ops = &minix_dir_aops;
} else if (S_ISLNK(inode->i_mode)) {
inode->i_op = &minix_symlink_inode_operations;
inode_nohighmem(inode);
--
2.47.3
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v2 3/4] minix: convert file operations to iomap and add
2026-06-28 5:15 [PATCH v2 0/4] minix: convert to iomap and add direct I/O Jeremy Bingham
2026-06-28 5:15 ` [PATCH v2 1/4] minix: add iomap infrastructure Jeremy Bingham
2026-06-28 5:15 ` [PATCH v2 2/4] minix: convert address space operations to iomap Jeremy Bingham
@ 2026-06-28 5:15 ` Jeremy Bingham
2026-06-28 5:15 ` [PATCH v2 4/4] minix: fix symlink and truncate for iomap Jeremy Bingham
3 siblings, 0 replies; 5+ messages in thread
From: Jeremy Bingham @ 2026-06-28 5:15 UTC (permalink / raw)
To: linux-fsdevel
Cc: linux-kernel, brauner, jkoolstra, jack, hch, viro, syzkaller,
Jeremy Bingham
Replace generic_file_read_iter and generic_file_write_iter with custom
minix_file_read_iter and minix_file_write_iter that dispatch to iomap
for both buffered and direct I/O.
Buffered writes now go through iomap_file_buffered_write instead of
the aops write_begin/write_end path (which no longer exists for
regular files). Buffered reads still use generic_file_read_iter
for the non-DIO case.
Direct I/O is implemented via iomap_dio_rw for both reads and writes.
minix_dio_read_iter takes a shared inode lock; minix_dio_write_iter
takes an exclusive lock, does generic_write_checks, and falls back
to buffered writes via iomap_file_buffered_write for the tail of a
DIO write that is not block-aligned. The minix_dio_write_end_io
callback updates i_size and marks the inode dirty.
minix_file_open sets FMODE_CAN_ODIRECT so the VFS allows O_DIRECT
opens, and splice_write is added to the file operations.
minix_setattr is exported (made non-static) so it can be shared by
the symlink inode operations in a subsequent patch.
Signed-off-by: Jeremy Bingham <jbingham@gmail.com>
---
fs/minix/file.c | 157 +++++++++++++++++++++++++++++++++++++++++++++--
fs/minix/minix.h | 2 +
2 files changed, 153 insertions(+), 6 deletions(-)
diff --git a/fs/minix/file.c b/fs/minix/file.c
index 86e5943cd2ff..b07c853fa43a 100644
--- a/fs/minix/file.c
+++ b/fs/minix/file.c
@@ -17,21 +17,166 @@ int minix_fsync(struct file *file, loff_t start, loff_t end, int datasync)
start, end, datasync);
}
+static ssize_t minix_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ struct inode *inode = iocb->ki_filp->f_mapping->host;
+ ssize_t ret;
+
+ inode_lock_shared(inode);
+
+ const struct iomap_ops *ops = minix_iomap_ops_ver(inode);
+
+ ret = iomap_dio_rw(iocb, to, ops, NULL, 0, NULL, 0);
+ inode_unlock_shared(inode);
+ return ret;
+}
+
+static int minix_dio_write_end_io(struct kiocb *iocb, ssize_t size, int error,
+ unsigned int flags)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ loff_t pos = iocb->ki_pos;
+
+ if (error)
+ return error;
+
+ pos += size;
+ if (size && pos > i_size_read(inode)) {
+ i_size_write(inode, pos);
+ mark_inode_dirty(inode);
+ }
+ return 0;
+}
+
+static const struct iomap_dio_ops minix_dio_write_ops = {
+ .end_io = minix_dio_write_end_io,
+};
+
+static ssize_t minix_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct inode *inode = iocb->ki_filp->f_mapping->host;
+ ssize_t ret;
+ unsigned int flags = 0;
+ unsigned long blocksize = inode->i_sb->s_blocksize;
+
+ inode_lock(inode);
+ ret = generic_write_checks(iocb, from);
+ if (ret <= 0)
+ goto out_unlock;
+
+ ret = kiocb_modified(iocb);
+ if (ret)
+ goto out_unlock;
+
+ if (iocb->ki_pos + iov_iter_count(from) > i_size_read(inode) ||
+ !IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(from), blocksize))
+ flags |= IOMAP_DIO_FORCE_WAIT;
+
+ const struct iomap_ops *ops = minix_iomap_ops_ver(inode);
+
+ ret = iomap_dio_rw(iocb, from, ops,
+ &minix_dio_write_ops, flags, NULL, 0);
+ if (ret == -ENOTBLK)
+ ret = 0; /* fallback to buffered */
+
+ if (ret >= 0 && iov_iter_count(from)) {
+ loff_t pos;
+ loff_t endbyte;
+ ssize_t status;
+
+ iocb->ki_flags &= ~IOCB_DIRECT;
+ pos = iocb->ki_pos;
+ status = iomap_file_buffered_write(iocb, from, ops,
+ NULL, NULL);
+ if (unlikely(status < 0)) {
+ ret = status;
+ goto out_unlock;
+ }
+
+ ret += status;
+ endbyte = pos + status - 1;
+ status = filemap_write_and_wait_range(inode->i_mapping, pos, endbyte);
+ if (!status) {
+ invalidate_mapping_pages(inode->i_mapping,
+ pos >> PAGE_SHIFT,
+ endbyte >> PAGE_SHIFT);
+ if (ret > 0)
+ ret = generic_write_sync(iocb, ret);
+ } else {
+ ret = status;
+ }
+ }
+
+out_unlock:
+ inode_unlock(inode);
+ return ret;
+}
+
+static ssize_t minix_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ if (iocb->ki_flags & IOCB_DIRECT)
+ return minix_dio_read_iter(iocb, to);
+
+ return generic_file_read_iter(iocb, to);
+}
+
+static ssize_t minix_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct inode *inode = iocb->ki_filp->f_mapping->host;
+ ssize_t ret;
+
+ /* minix_dio_write_iter also locks the inode and appears to do the same
+ * general sorts of checks as this, so just return directly from there.
+ */
+ if (iocb->ki_flags & IOCB_DIRECT)
+ return minix_dio_write_iter(iocb, from);
+
+ inode_lock(inode);
+ ret = generic_write_checks(iocb, from);
+ if (ret <= 0)
+ goto unlock;
+
+ ret = file_modified(iocb->ki_filp);
+ if (ret)
+ goto unlock;
+
+ const struct iomap_ops *ops = minix_iomap_ops_ver(inode);
+
+ ret = iomap_file_buffered_write(iocb, from, ops,
+ NULL, NULL);
+
+ if (ret > 0)
+ ret = generic_write_sync(iocb, ret);
+
+unlock:
+ inode_unlock(inode);
+ return ret;
+}
+
+static int minix_file_open(struct inode *inode, struct file *filp)
+{
+ filp->f_mode |= FMODE_CAN_ODIRECT;
+ return generic_file_open(inode, filp);
+}
+
/*
- * We have mostly NULLs here: the current defaults are OK for
- * the minix filesystem.
+ * We still have some NULLs here, but not as many of the current defaults are
+ * still OK for the minix filesystem.
*/
+
const struct file_operations minix_file_operations = {
.llseek = generic_file_llseek,
- .read_iter = generic_file_read_iter,
- .write_iter = generic_file_write_iter,
+ .read_iter = minix_file_read_iter,
+ .write_iter = minix_file_write_iter,
.mmap_prepare = generic_file_mmap_prepare,
+ .open = minix_file_open,
.fsync = minix_fsync,
.splice_read = filemap_splice_read,
+ .splice_write = iter_file_splice_write,
};
-static int minix_setattr(struct mnt_idmap *idmap,
- struct dentry *dentry, struct iattr *attr)
+int minix_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+ struct iattr *attr)
{
struct inode *inode = d_inode(dentry);
int error;
diff --git a/fs/minix/minix.h b/fs/minix/minix.h
index 77e503cca97f..76718f789369 100644
--- a/fs/minix/minix.h
+++ b/fs/minix/minix.h
@@ -58,6 +58,8 @@ void minix_free_block(struct inode *inode, unsigned long block);
unsigned long minix_count_free_blocks(struct super_block *sb);
int minix_getattr(struct mnt_idmap *, const struct path *,
struct kstat *, u32, unsigned int);
+int minix_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+ struct iattr *attr);
int minix_prepare_chunk(struct folio *folio, loff_t pos, unsigned len);
struct mapping_metadata_bhs *minix_get_metadata_bhs(struct inode *inode);
int minix_fsync(struct file *file, loff_t start, loff_t end, int datasync);
--
2.47.3
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v2 4/4] minix: fix symlink and truncate for iomap
2026-06-28 5:15 [PATCH v2 0/4] minix: convert to iomap and add direct I/O Jeremy Bingham
` (2 preceding siblings ...)
2026-06-28 5:15 ` [PATCH v2 3/4] minix: convert file operations to iomap and add Jeremy Bingham
@ 2026-06-28 5:15 ` Jeremy Bingham
3 siblings, 0 replies; 5+ messages in thread
From: Jeremy Bingham @ 2026-06-28 5:15 UTC (permalink / raw)
To: linux-fsdevel
Cc: linux-kernel, brauner, jkoolstra, jack, hch, viro, syzkaller,
Jeremy Bingham
The original minix iomap conversion patches had a couple of issues
exposed by syzbot:
1. NULL pointer dereferences in page_symlink. Since the iomap based
minix_aops no longer used write_begin and write_end, when page_link
attempted to call aops->write_begin there was a crash because there was
no longer a pointer assigned to aops->write_begin. This was fixed with a
custom function that writes the symlink target directly to a newly
allocated data block acquired with minix_new_block and sb_getblk, thus
bypassing the aops write path entirely. The symlink read path was in
turn replaced with a new minix_get_link that reads the target from the
first data block directly with sb_bread, similar to how ext4_get_link
does it.
2. Truncate crashed. There was a conflict in minix's truncate() function
between buffer_head and iomap where block_truncate_page was attaching
buffer_heads to folios, but this ran up against how iomap works. Fixed
this by using iomap_truncate_page for inodes using minix_aops and
block_truncate_page for inodes with minix_dir_aops.
Also, minix_symlink_inode_operations now has .setattr = minix_setattr so
symlinks can be truncated more properly through iomap rather than using
the default simple_setattr.
Signed-off-by: Jeremy Bingham <jbingham@gmail.com>
---
fs/minix/inode.c | 4 +-
fs/minix/itree_common.c | 11 +++-
fs/minix/minix.h | 5 +-
fs/minix/namei.c | 137 +++++++++++++++++++++++++++++++++++++++-
4 files changed, 152 insertions(+), 5 deletions(-)
diff --git a/fs/minix/inode.c b/fs/minix/inode.c
index 2ba6766fce51..b113c44764ff 100644
--- a/fs/minix/inode.c
+++ b/fs/minix/inode.c
@@ -573,8 +573,9 @@ static const struct address_space_operations minix_dir_aops = {
};
static const struct inode_operations minix_symlink_inode_operations = {
- .get_link = page_get_link,
+ .get_link = minix_get_link,
.getattr = minix_getattr,
+ .setattr = minix_setattr,
};
void minix_set_inode(struct inode *inode, dev_t rdev)
@@ -838,4 +839,3 @@ module_init(init_minix_fs)
module_exit(exit_minix_fs)
MODULE_DESCRIPTION("Minix file system");
MODULE_LICENSE("GPL");
-
diff --git a/fs/minix/itree_common.c b/fs/minix/itree_common.c
index c3cd2c75af9c..5a8b73a7beda 100644
--- a/fs/minix/itree_common.c
+++ b/fs/minix/itree_common.c
@@ -311,7 +311,16 @@ static inline void truncate (struct inode * inode)
long iblock;
iblock = (inode->i_size + sb->s_blocksize -1) >> sb->s_blocksize_bits;
- block_truncate_page(inode->i_mapping, inode->i_size, get_block);
+
+ /* Depending on what address space operations are being used by the
+ * inode being truncated, we need to either call iomap_truncate_page or
+ * block_truncate_page.
+ */
+ if (inode->i_mapping->a_ops == &minix_aops)
+ iomap_truncate_page(inode, inode->i_size, NULL,
+ minix_iomap_ops_ver(inode), NULL, NULL);
+ else
+ block_truncate_page(inode->i_mapping, inode->i_size, get_block);
n = block_to_path(inode, iblock, offsets);
if (!n)
diff --git a/fs/minix/minix.h b/fs/minix/minix.h
index 76718f789369..d1a890e96abe 100644
--- a/fs/minix/minix.h
+++ b/fs/minix/minix.h
@@ -57,7 +57,7 @@ int minix_new_block(struct inode *inode);
void minix_free_block(struct inode *inode, unsigned long block);
unsigned long minix_count_free_blocks(struct super_block *sb);
int minix_getattr(struct mnt_idmap *, const struct path *,
- struct kstat *, u32, unsigned int);
+ struct kstat *, u32, unsigned);
int minix_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
struct iattr *attr);
int minix_prepare_chunk(struct folio *folio, loff_t pos, unsigned len);
@@ -82,6 +82,9 @@ int minix_make_empty(struct inode*, struct inode*);
int minix_empty_dir(struct inode*);
int minix_set_link(struct minix_dir_entry *de, struct folio *folio,
struct inode *inode);
+extern const char *minix_get_link(struct dentry *dentry, struct inode *inode,
+ struct delayed_call *callback);
+
struct minix_dir_entry *minix_dotdot(struct inode*, struct folio **);
ino_t minix_inode_by_name(struct dentry*);
diff --git a/fs/minix/namei.c b/fs/minix/namei.c
index 263e4ba8b1c8..e245f55a68ff 100644
--- a/fs/minix/namei.c
+++ b/fs/minix/namei.c
@@ -6,6 +6,8 @@
*/
#include "minix.h"
+#include <linux/buffer_head.h>
+#include <linux/namei.h>
static int add_nondir(struct dentry *dentry, struct inode *inode)
{
@@ -69,6 +71,101 @@ static int minix_create(struct mnt_idmap *idmap, struct inode *dir,
return minix_mknod(&nop_mnt_idmap, dir, dentry, mode, 0);
}
+static inline u16 *v1_i_data(struct inode *inode)
+{
+ return (u16 *)minix_i(inode)->u.i1_data;
+}
+
+static inline u32 *v2_i_data(struct inode *inode)
+{
+ return (u32 *)minix_i(inode)->u.i2_data;
+}
+
+static inline u16 cpu_to_v1_block(sector_t n)
+{
+ return n;
+}
+
+static inline u32 cpu_to_v2_block(sector_t n)
+{
+ return n;
+}
+
+static inline sector_t v1_block_to_cpu(u16 n)
+{
+ return n;
+}
+
+static inline sector_t v2_block_to_cpu(u32 n)
+{
+ return n;
+}
+
+/* Reimplement page_symlink's general logic while avoiding using buffer head
+ * based aops operations like aops->write_begin so things behave better with
+ * the new regime of iomap based aops operations. Cribbing from page_symlink in
+ * fs/namei.c and ext4's ext4_init_symlink_block.
+ */
+static int __page_symlink(struct inode *inode, const char *symname, int len)
+{
+ struct super_block *sb = inode->i_sb;
+ struct buffer_head *bh;
+ char *kaddr;
+ int err = 0;
+ u16 *p16; /* v1 16 bit block */
+ u32 *p32; /* v2/3 32 bit block */
+
+ sector_t phys;
+
+ phys = minix_new_block(inode);
+ if (!phys) {
+ err = -ENOSPC;
+ goto ps_out;
+ }
+
+ if (INODE_VERSION(inode) == MINIX_V1) {
+ p16 = v1_i_data(inode);
+ *p16 = cpu_to_v1_block(phys);
+ } else {
+ p32 = v2_i_data(inode);
+ *p32 = cpu_to_v2_block(phys);
+ }
+
+ bh = sb_getblk(sb, phys);
+ if (!bh) {
+ err = -ENOMEM;
+ goto ps_fail;
+ }
+
+ lock_buffer(bh);
+ kaddr = (char *)bh->b_data;
+ memset(kaddr, 0, sb->s_blocksize);
+ memcpy(kaddr, symname, len);
+ inode->i_size = len - 1;
+ set_buffer_uptodate(bh);
+ unlock_buffer(bh);
+
+ mmb_mark_buffer_dirty(bh, &minix_i(inode)->i_metadata_bhs);
+ if (inode_needs_sync(inode)) {
+ sync_dirty_buffer(bh);
+ if (buffer_req(bh) && !buffer_uptodate(bh)) {
+ pr_err("i/o error syncing itable block");
+ err = -EIO;
+ }
+
+ }
+
+ mark_inode_dirty(inode);
+ brelse(bh);
+
+ps_out:
+ return err;
+
+ps_fail:
+ minix_free_block(inode, phys);
+ goto ps_out;
+}
+
static int minix_symlink(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, const char *symname)
{
@@ -84,7 +181,7 @@ static int minix_symlink(struct mnt_idmap *idmap, struct inode *dir,
return PTR_ERR(inode);
minix_set_inode(inode, 0);
- err = page_symlink(inode, symname, i);
+ err = __page_symlink(inode, symname, i);
if (unlikely(err)) {
inode_dec_link_count(inode);
iput(inode);
@@ -273,6 +370,44 @@ static int minix_rename(struct mnt_idmap *idmap,
return err;
}
+/* straight up thievery here; stolen verbatim from ext4_get_link */
+static void minix_free_link(void *bh)
+{
+ brelse(bh);
+}
+
+/* Borrowing from ext4_get_link to a degree; since minix inodes and symlinks
+ * are significantly simpler, we don't need to do nearly as much as ext4
+ * requires for old-timey ext4 slow links.
+ */
+const char *minix_get_link(struct dentry *dentry, struct inode *inode,
+ struct delayed_call *callback)
+{
+ struct super_block *sb = inode->i_sb;
+ struct buffer_head *bh;
+ sector_t blk;
+
+ /* Get yon block, depending on what version of the minix fs this is. */
+ if (INODE_VERSION(inode) == MINIX_V1)
+ blk = v1_block_to_cpu(*(v1_i_data(inode)));
+ else
+ blk = v2_block_to_cpu(*(v2_i_data(inode)));
+
+ bh = sb_bread(sb, blk);
+ if (IS_ERR(bh))
+ return ERR_CAST(bh);
+ if (!bh) {
+ pr_err("bad symlink on inode %llu", inode->i_ino);
+ return ERR_PTR(-EFSCORRUPTED);
+ }
+
+ set_delayed_call(callback, minix_free_link, bh);
+ nd_terminate_link(bh->b_data, inode->i_size,
+ inode->i_sb->s_blocksize - 1);
+
+ return bh->b_data;
+}
+
/*
* directories can handle most operations...
*/
--
2.47.3
^ permalink raw reply related [flat|nested] 5+ messages in thread