[PATCH v4 03/11] fs/9p: Consolidate file operations and add readahead and writeback

From: Eric Van Hensbergen
Date: Fri Feb 17 2023 - 19:44:15 EST

We had 3 different sets of file operations across 2 different protocol
variants differentiated by cache which really only changed 3
functions. But the real problem is that certain file modes, mount
options, and other factors weren't being considered when we
decided whether or not to use caches.

This consolidates all the operations and switches
to conditionals within a common set to decide whether or not
to do different aspects of caching.

Signed-off-by: Eric Van Hensbergen <ericvh@xxxxxxxxxx>
---
fs/9p/v9fs.c | 30 ++++------
fs/9p/v9fs.h | 3 +
fs/9p/v9fs_vfs.h | 4 --
fs/9p/vfs_dir.c | 3 +
fs/9p/vfs_file.c | 131 +++++++----------------------------------
fs/9p/vfs_inode.c | 62 ++++++++++++-------
fs/9p/vfs_inode_dotl.c | 22 +++++--
7 files changed, 98 insertions(+), 157 deletions(-)

diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index 61a51b90600d..a46bf9121f11 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -39,8 +39,6 @@ enum {
Opt_uname, Opt_remotename, Opt_cache, Opt_cachetag,
/* Options that take no arguments */
Opt_nodevmap,
- /* Cache options */
- Opt_cache_loose, Opt_fscache, Opt_mmap,
/* Access options */
Opt_access, Opt_posixacl,
/* Lock timeout option */
@@ -58,9 +56,6 @@ static const match_table_t tokens = {
{Opt_remotename, "aname=%s"},
{Opt_nodevmap, "nodevmap"},
{Opt_cache, "cache=%s"},
- {Opt_cache_loose, "loose"},
- {Opt_fscache, "fscache"},
- {Opt_mmap, "mmap"},
{Opt_cachetag, "cachetag=%s"},
{Opt_access, "access=%s"},
{Opt_posixacl, "posixacl"},
@@ -69,10 +64,12 @@ static const match_table_t tokens = {
};

static const char *const v9fs_cache_modes[nr__p9_cache_modes] = {
- [CACHE_NONE] = "none",
- [CACHE_MMAP] = "mmap",
- [CACHE_LOOSE] = "loose",
- [CACHE_FSCACHE] = "fscache",
+ [CACHE_NONE] = "none",
+ [CACHE_READAHEAD] = "readahead",
+ [CACHE_WRITEBACK] = "writeback",
+ [CACHE_MMAP] = "mmap",
+ [CACHE_LOOSE] = "loose",
+ [CACHE_FSCACHE] = "fscache",
};

/* Interpret mount options for cache mode */
@@ -89,6 +86,12 @@ static int get_cache_mode(char *s)
} else if (!strcmp(s, "mmap")) {
version = CACHE_MMAP;
p9_debug(P9_DEBUG_9P, "Cache mode: mmap\n");
+ } else if (!strcmp(s, "writeback")) {
+ version = CACHE_WRITEBACK;
+ p9_debug(P9_DEBUG_9P, "Cache mode: writeback\n");
+ } else if (!strcmp(s, "readahead")) {
+ version = CACHE_READAHEAD;
+ p9_debug(P9_DEBUG_9P, "Cache mode: readahead\n");
} else if (!strcmp(s, "none")) {
version = CACHE_NONE;
p9_debug(P9_DEBUG_9P, "Cache mode: none\n");
@@ -266,15 +269,6 @@ static int v9fs_parse_options(struct v9fs_session_info *v9ses, char *opts)
case Opt_nodevmap:
v9ses->nodev = 1;
break;
- case Opt_cache_loose:
- v9ses->cache = CACHE_LOOSE;
- break;
- case Opt_fscache:
- v9ses->cache = CACHE_FSCACHE;
- break;
- case Opt_mmap:
- v9ses->cache = CACHE_MMAP;
- break;
case Opt_cachetag:
#ifdef CONFIG_9P_FSCACHE
kfree(v9ses->cachetag);
diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index 6acabc2e7dc9..517b2201ad24 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -51,6 +51,8 @@ enum p9_session_flags {
enum p9_cache_modes {
CACHE_NONE,
CACHE_MMAP,
+ CACHE_READAHEAD,
+ CACHE_WRITEBACK,
CACHE_LOOSE,
CACHE_FSCACHE,
nr__p9_cache_modes
@@ -155,6 +157,7 @@ extern int v9fs_vfs_rename(struct user_namespace *mnt_userns,
struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags);
+extern int v9fs_flush_inode_writeback(struct inode *inode);
extern struct inode *v9fs_inode_from_fid(struct v9fs_session_info *v9ses,
struct p9_fid *fid,
struct super_block *sb, int new);
diff --git a/fs/9p/v9fs_vfs.h b/fs/9p/v9fs_vfs.h
index bc417da7e9c1..cce87c9bdd8b 100644
--- a/fs/9p/v9fs_vfs.h
+++ b/fs/9p/v9fs_vfs.h
@@ -36,10 +36,6 @@ extern const struct file_operations v9fs_dir_operations;
extern const struct file_operations v9fs_dir_operations_dotl;
extern const struct dentry_operations v9fs_dentry_operations;
extern const struct dentry_operations v9fs_cached_dentry_operations;
-extern const struct file_operations v9fs_cached_file_operations;
-extern const struct file_operations v9fs_cached_file_operations_dotl;
-extern const struct file_operations v9fs_mmap_file_operations;
-extern const struct file_operations v9fs_mmap_file_operations_dotl;
extern struct kmem_cache *v9fs_inode_cache;

struct inode *v9fs_alloc_inode(struct super_block *sb);
diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
index 59b0e8948f78..bd31593437f3 100644
--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -214,6 +214,9 @@ int v9fs_dir_release(struct inode *inode, struct file *filp)
p9_debug(P9_DEBUG_VFS, "inode: %p filp: %p fid: %d\n",
inode, filp, fid ? fid->fid : -1);
if (fid) {
+ if ((fid->qid.type == P9_QTFILE) && (filp->f_mode & FMODE_WRITE))
+ v9fs_flush_inode_writeback(inode);
+
spin_lock(&inode->i_lock);
hlist_del(&fid->ilist);
spin_unlock(&inode->i_lock);
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 3b6458846a0b..20e4bd299fc2 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -28,7 +28,6 @@
#include "fid.h"
#include "cache.h"

-static const struct vm_operations_struct v9fs_file_vm_ops;
static const struct vm_operations_struct v9fs_mmap_file_vm_ops;

/**
@@ -73,7 +72,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
}

mutex_lock(&v9inode->v_mutex);
- if ((v9ses->cache) && !v9inode->writeback_fid &&
+ if ((v9ses->cache >= CACHE_WRITEBACK) && !v9inode->writeback_fid &&
((file->f_flags & O_ACCMODE) != O_RDONLY)) {
/*
* clone a fid and add it to writeback_fid
@@ -367,10 +366,15 @@ v9fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct p9_fid *fid = iocb->ki_filp->private_data;
int ret, err = 0;
+ struct inode *inode = file_inode(iocb->ki_filp);
+ struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);

p9_debug(P9_DEBUG_VFS, "count %zu offset %lld\n",
iov_iter_count(to), iocb->ki_pos);

+ if (v9ses->cache > CACHE_MMAP)
+ return generic_file_read_iter(iocb, to);
+
if (iocb->ki_filp->f_flags & O_NONBLOCK)
ret = p9_client_read_once(fid, iocb->ki_pos, to, &err);
else
@@ -395,6 +399,11 @@ v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
ssize_t retval;
loff_t origin;
int err = 0;
+ struct inode *inode = file_inode(iocb->ki_filp);
+ struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
+
+ if (v9ses->cache >= CACHE_WRITEBACK)
+ return generic_file_write_iter(iocb, from);

retval = generic_write_checks(iocb, from);
if (retval <= 0)
@@ -477,25 +486,16 @@ static int
v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
{
int retval;
-
-
- retval = generic_file_mmap(filp, vma);
- if (!retval)
- vma->vm_ops = &v9fs_file_vm_ops;
-
- return retval;
-}
-
-static int
-v9fs_mmap_file_mmap(struct file *filp, struct vm_area_struct *vma)
-{
- int retval;
- struct inode *inode;
- struct v9fs_inode *v9inode;
+ struct inode *inode = file_inode(filp);
+ struct v9fs_inode *v9inode = V9FS_I(inode);
+ struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
struct p9_fid *fid;

- inode = file_inode(filp);
- v9inode = V9FS_I(inode);
+ if (v9ses->cache < CACHE_MMAP) {
+ invalidate_inode_pages2(filp->f_mapping);
+ return generic_file_readonly_mmap(filp, vma);
+ }
+
mutex_lock(&v9inode->v_mutex);
if (!v9inode->writeback_fid &&
(vma->vm_flags & VM_SHARED) &&
@@ -563,35 +563,6 @@ v9fs_vm_page_mkwrite(struct vm_fault *vmf)
return VM_FAULT_NOPAGE;
}

-/**
- * v9fs_mmap_file_read_iter - read from a file
- * @iocb: The operation parameters
- * @to: The buffer to read into
- *
- */
-static ssize_t
-v9fs_mmap_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
-{
- /* TODO: Check if there are dirty pages */
- return v9fs_file_read_iter(iocb, to);
-}
-
-/**
- * v9fs_mmap_file_write_iter - write to a file
- * @iocb: The operation parameters
- * @from: The data to write
- *
- */
-static ssize_t
-v9fs_mmap_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
-{
- /*
- * TODO: invalidate mmaps on filp's inode between
- * offset and offset+count
- */
- return v9fs_file_write_iter(iocb, from);
-}
-
static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
{
struct inode *inode;
@@ -614,13 +585,6 @@ static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
filemap_fdatawrite_wbc(inode->i_mapping, &wbc);
}

-
-static const struct vm_operations_struct v9fs_file_vm_ops = {
- .fault = filemap_fault,
- .map_pages = filemap_map_pages,
- .page_mkwrite = v9fs_vm_page_mkwrite,
-};
-
static const struct vm_operations_struct v9fs_mmap_file_vm_ops = {
.close = v9fs_mmap_vm_close,
.fault = filemap_fault,
@@ -628,34 +592,6 @@ static const struct vm_operations_struct v9fs_mmap_file_vm_ops = {
.page_mkwrite = v9fs_vm_page_mkwrite,
};

-
-const struct file_operations v9fs_cached_file_operations = {
- .llseek = generic_file_llseek,
- .read_iter = generic_file_read_iter,
- .write_iter = generic_file_write_iter,
- .open = v9fs_file_open,
- .release = v9fs_dir_release,
- .lock = v9fs_file_lock,
- .mmap = v9fs_file_mmap,
- .splice_read = generic_file_splice_read,
- .splice_write = iter_file_splice_write,
- .fsync = v9fs_file_fsync,
-};
-
-const struct file_operations v9fs_cached_file_operations_dotl = {
- .llseek = generic_file_llseek,
- .read_iter = generic_file_read_iter,
- .write_iter = generic_file_write_iter,
- .open = v9fs_file_open,
- .release = v9fs_dir_release,
- .lock = v9fs_file_lock_dotl,
- .flock = v9fs_file_flock_dotl,
- .mmap = v9fs_file_mmap,
- .splice_read = generic_file_splice_read,
- .splice_write = iter_file_splice_write,
- .fsync = v9fs_file_fsync_dotl,
-};
-
const struct file_operations v9fs_file_operations = {
.llseek = generic_file_llseek,
.read_iter = v9fs_file_read_iter,
@@ -677,34 +613,7 @@ const struct file_operations v9fs_file_operations_dotl = {
.release = v9fs_dir_release,
.lock = v9fs_file_lock_dotl,
.flock = v9fs_file_flock_dotl,
- .mmap = generic_file_readonly_mmap,
- .splice_read = generic_file_splice_read,
- .splice_write = iter_file_splice_write,
- .fsync = v9fs_file_fsync_dotl,
-};
-
-const struct file_operations v9fs_mmap_file_operations = {
- .llseek = generic_file_llseek,
- .read_iter = v9fs_mmap_file_read_iter,
- .write_iter = v9fs_mmap_file_write_iter,
- .open = v9fs_file_open,
- .release = v9fs_dir_release,
- .lock = v9fs_file_lock,
- .mmap = v9fs_mmap_file_mmap,
- .splice_read = generic_file_splice_read,
- .splice_write = iter_file_splice_write,
- .fsync = v9fs_file_fsync,
-};
-
-const struct file_operations v9fs_mmap_file_operations_dotl = {
- .llseek = generic_file_llseek,
- .read_iter = v9fs_mmap_file_read_iter,
- .write_iter = v9fs_mmap_file_write_iter,
- .open = v9fs_file_open,
- .release = v9fs_dir_release,
- .lock = v9fs_file_lock_dotl,
- .flock = v9fs_file_flock_dotl,
- .mmap = v9fs_mmap_file_mmap,
+ .mmap = v9fs_file_mmap,
.splice_read = generic_file_splice_read,
.splice_write = iter_file_splice_write,
.fsync = v9fs_file_fsync_dotl,
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 33e521c60e2c..8ffa6631b1fd 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -219,6 +219,35 @@ v9fs_blank_wstat(struct p9_wstat *wstat)
wstat->extension = NULL;
}

+/**
+ * v9fs_flush_inode_writeback - writeback any data associated with inode
+ * @inode: inode to writeback
+ *
+ * This is used to make sure anything that needs to be written
+ * to server gets flushed before we do certain operations (setattr, getattr, close)
+ *
+ */
+
+int v9fs_flush_inode_writeback(struct inode *inode)
+{
+ struct writeback_control wbc = {
+ .nr_to_write = LONG_MAX,
+ .sync_mode = WB_SYNC_ALL,
+ .range_start = 0,
+ .range_end = -1,
+ };
+
+ int retval = filemap_fdatawrite_wbc(inode->i_mapping, &wbc);
+
+ if (retval != 0) {
+ p9_debug(P9_DEBUG_ERROR,
+ "trying to flush inode %p failed with error code %d\n",
+ inode, retval);
+ }
+
+ return retval;
+}
+
/**
* v9fs_alloc_inode - helper function to allocate an inode
* @sb: The superblock to allocate the inode from
@@ -287,24 +316,10 @@ int v9fs_init_inode(struct v9fs_session_info *v9ses,
case S_IFREG:
if (v9fs_proto_dotl(v9ses)) {
inode->i_op = &v9fs_file_inode_operations_dotl;
- if (v9ses->cache == CACHE_LOOSE ||
- v9ses->cache == CACHE_FSCACHE)
- inode->i_fop =
- &v9fs_cached_file_operations_dotl;
- else if (v9ses->cache == CACHE_MMAP)
- inode->i_fop = &v9fs_mmap_file_operations_dotl;
- else
- inode->i_fop = &v9fs_file_operations_dotl;
+ inode->i_fop = &v9fs_file_operations_dotl;
} else {
inode->i_op = &v9fs_file_inode_operations;
- if (v9ses->cache == CACHE_LOOSE ||
- v9ses->cache == CACHE_FSCACHE)
- inode->i_fop =
- &v9fs_cached_file_operations;
- else if (v9ses->cache == CACHE_MMAP)
- inode->i_fop = &v9fs_mmap_file_operations;
- else
- inode->i_fop = &v9fs_file_operations;
+ inode->i_fop = &v9fs_file_operations;
}

break;
@@ -843,7 +858,7 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
inode = d_inode(dentry);
v9inode = V9FS_I(inode);
mutex_lock(&v9inode->v_mutex);
- if ((v9ses->cache) && !v9inode->writeback_fid &&
+ if ((v9ses->cache >= CACHE_WRITEBACK) && !v9inode->writeback_fid &&
((flags & O_ACCMODE) != O_RDONLY)) {
/*
* clone a fid and add it to writeback_fid
@@ -1030,6 +1045,7 @@ v9fs_vfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
struct kstat *stat, u32 request_mask, unsigned int flags)
{
struct dentry *dentry = path->dentry;
+ struct inode *inode = d_inode(dentry);
struct v9fs_session_info *v9ses;
struct p9_fid *fid;
struct p9_wstat *st;
@@ -1039,6 +1055,9 @@ v9fs_vfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
generic_fillattr(&init_user_ns, d_inode(dentry), stat);
return 0;
+ } else if (v9ses->cache >= CACHE_WRITEBACK) {
+ if (S_ISREG(inode->i_mode))
+ v9fs_flush_inode_writeback(inode);
}
fid = v9fs_fid_lookup(dentry);
if (IS_ERR(fid))
@@ -1116,7 +1135,7 @@ static int v9fs_vfs_setattr(struct user_namespace *mnt_userns,

/* Write all dirty data */
if (d_is_reg(dentry))
- filemap_write_and_wait(inode->i_mapping);
+ v9fs_flush_inode_writeback(inode);

retval = p9_client_wstat(fid, &wstat);

@@ -1127,9 +1146,12 @@ static int v9fs_vfs_setattr(struct user_namespace *mnt_userns,
return retval;

if ((iattr->ia_valid & ATTR_SIZE) &&
- iattr->ia_size != i_size_read(inode)) {
+ iattr->ia_size != i_size_read(inode)) {
truncate_setsize(inode, iattr->ia_size);
- fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
+ if (v9ses->cache == CACHE_FSCACHE)
+ fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
+ else
+ invalidate_mapping_pages(&inode->i_data, 0, -1);
}

v9fs_invalidate_inode_attr(inode);
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index bff37a312e64..4f01808c3bae 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -458,6 +458,7 @@ v9fs_vfs_getattr_dotl(struct user_namespace *mnt_userns,
struct dentry *dentry = path->dentry;
struct v9fs_session_info *v9ses;
struct p9_fid *fid;
+ struct inode *inode = d_inode(dentry);
struct p9_stat_dotl *st;

p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
@@ -465,6 +466,10 @@ v9fs_vfs_getattr_dotl(struct user_namespace *mnt_userns,
if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
generic_fillattr(&init_user_ns, d_inode(dentry), stat);
return 0;
+ } else if (v9ses->cache >= CACHE_WRITEBACK) {
+ if (S_ISREG(inode->i_mode))
+ v9fs_flush_inode_writeback(inode);
+
}
fid = v9fs_fid_lookup(dentry);
if (IS_ERR(fid))
@@ -540,12 +545,14 @@ int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
struct dentry *dentry, struct iattr *iattr)
{
int retval, use_dentry = 0;
+ struct inode *inode = d_inode(dentry);
+ struct v9fs_inode *v9inode = V9FS_I(inode);
+ struct v9fs_session_info *v9ses;
struct p9_fid *fid = NULL;
struct p9_iattr_dotl p9attr = {
.uid = INVALID_UID,
.gid = INVALID_GID,
};
- struct inode *inode = d_inode(dentry);

p9_debug(P9_DEBUG_VFS, "\n");

@@ -553,6 +560,8 @@ int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
if (retval)
return retval;

+ v9ses = v9fs_dentry2v9ses(dentry);
+
p9attr.valid = v9fs_mapped_iattr_valid(iattr->ia_valid);
if (iattr->ia_valid & ATTR_MODE)
p9attr.mode = iattr->ia_mode;
@@ -584,7 +593,7 @@ int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,

/* Write all dirty data */
if (S_ISREG(inode->i_mode))
- filemap_write_and_wait(inode->i_mapping);
+ v9fs_flush_inode_writeback(inode);

retval = p9_client_setattr(fid, &p9attr);
if (retval < 0) {
@@ -593,9 +602,14 @@ int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
return retval;
}

- if ((iattr->ia_valid & ATTR_SIZE) &&
- iattr->ia_size != i_size_read(inode))
+ if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size !=
+ i_size_read(inode)) {
truncate_setsize(inode, iattr->ia_size);
+ if (v9ses->cache == CACHE_FSCACHE)
+ fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
+ else
+ invalidate_mapping_pages(&inode->i_data, 0, -1);
+ }

v9fs_invalidate_inode_attr(inode);
setattr_copy(&init_user_ns, inode, iattr);
--
2.37.2