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Subject[PATCH 07/23] vfs: Teach sendfile,splice,tee,and vmsplice to use file_hotplug_lock
From: Eric W. Biederman <ebiederm@maxwell.arastra.com>

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
---
fs/read_write.c | 28 +++++++++----
fs/splice.c | 111 +++++++++++++++++++++++++++++++++++++-----------------
2 files changed, 95 insertions(+), 44 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 718baea..c473d74 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -861,21 +861,24 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
goto out;
if (!(in_file->f_mode & FMODE_READ))
goto fput_in;
+ retval = -EIO;
+ if (!file_hotplug_read_trylock(in_file))
+ goto fput_in;
retval = -EINVAL;
in_inode = in_file->f_path.dentry->d_inode;
if (!in_inode)
- goto fput_in;
+ goto unlock_in;
if (!in_file->f_op || !in_file->f_op->splice_read)
- goto fput_in;
+ goto unlock_in;
retval = -ESPIPE;
if (!ppos)
ppos = &in_file->f_pos;
else
if (!(in_file->f_mode & FMODE_PREAD))
- goto fput_in;
+ goto unlock_in;
retval = rw_verify_area(READ, in_file, ppos, count);
if (retval < 0)
- goto fput_in;
+ goto unlock_in;
count = retval;

/*
@@ -884,16 +887,19 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
retval = -EBADF;
out_file = fget_light(out_fd, &fput_needed_out);
if (!out_file)
- goto fput_in;
+ goto unlock_in;
if (!(out_file->f_mode & FMODE_WRITE))
goto fput_out;
+ retval = -EIO;
+ if (!file_hotplug_read_trylock(out_file))
+ goto fput_out;
retval = -EINVAL;
if (!out_file->f_op || !out_file->f_op->sendpage)
- goto fput_out;
+ goto unlock_out;
out_inode = out_file->f_path.dentry->d_inode;
retval = rw_verify_area(WRITE, out_file, &out_file->f_pos, count);
if (retval < 0)
- goto fput_out;
+ goto unlock_out;
count = retval;

if (!max)
@@ -902,11 +908,11 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
pos = *ppos;
retval = -EINVAL;
if (unlikely(pos < 0))
- goto fput_out;
+ goto unlock_out;
if (unlikely(pos + count > max)) {
retval = -EOVERFLOW;
if (pos >= max)
- goto fput_out;
+ goto unlock_out;
count = max - pos;
}

@@ -933,8 +939,12 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
if (*ppos > max)
retval = -EOVERFLOW;

+unlock_out:
+ file_hotplug_read_unlock(out_file);
fput_out:
fput_light(out_file, fput_needed_out);
+unlock_in:
+ file_hotplug_read_unlock(in_file);
fput_in:
fput_light(in_file, fput_needed_in);
out:
diff --git a/fs/splice.c b/fs/splice.c
index 666953d..fc6b3a5 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1464,15 +1464,21 @@ SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov,

error = -EBADF;
file = fget_light(fd, &fput);
- if (file) {
- if (file->f_mode & FMODE_WRITE)
- error = vmsplice_to_pipe(file, iov, nr_segs, flags);
- else if (file->f_mode & FMODE_READ)
- error = vmsplice_to_user(file, iov, nr_segs, flags);
+ if (!file)
+ goto out;

- fput_light(file, fput);
- }
+ if (!file_hotplug_read_trylock(file))
+ goto fput_file;

+ if (file->f_mode & FMODE_WRITE)
+ error = vmsplice_to_pipe(file, iov, nr_segs, flags);
+ else if (file->f_mode & FMODE_READ)
+ error = vmsplice_to_user(file, iov, nr_segs, flags);
+
+ file_hotplug_read_unlock(file);
+fput_file:
+ fput_light(file, fput);
+out:
return error;
}

@@ -1489,21 +1495,39 @@ SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,

error = -EBADF;
in = fget_light(fd_in, &fput_in);
- if (in) {
- if (in->f_mode & FMODE_READ) {
- out = fget_light(fd_out, &fput_out);
- if (out) {
- if (out->f_mode & FMODE_WRITE)
- error = do_splice(in, off_in,
- out, off_out,
- len, flags);
- fput_light(out, fput_out);
- }
- }
+ if (!in)
+ goto out;

- fput_light(in, fput_in);
- }
+ if (!(in->f_mode & FMODE_READ))
+ goto fput_in;
+
+ error = -EIO;
+ if (!file_hotplug_read_trylock(in))
+ goto fput_in;
+
+ error = -EBADF;
+ out = fget_light(fd_out, &fput_out);
+ if (!out)
+ goto unlock_in;
+
+ if (!(out->f_mode & FMODE_WRITE))
+ goto fput_out;
+
+ error = -EIO;
+ if (!file_hotplug_read_trylock(out))
+ goto fput_out;
+
+ error = do_splice(in, off_in, out, off_out, len, flags);

+ file_hotplug_read_unlock(out);
+fput_out:
+ fput_light(out, fput_out);
+unlock_in:
+ file_hotplug_read_unlock(in);
+fput_in:
+ fput_light(in, fput_in);
+
+out:
return error;
}

@@ -1703,27 +1727,44 @@ static long do_tee(struct file *in, struct file *out, size_t len,

SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
{
- struct file *in;
- int error, fput_in;
+ struct file *in, *out;
+ int error, fput_in, fput_out;

if (unlikely(!len))
return 0;

error = -EBADF;
in = fget_light(fdin, &fput_in);
- if (in) {
- if (in->f_mode & FMODE_READ) {
- int fput_out;
- struct file *out = fget_light(fdout, &fput_out);
-
- if (out) {
- if (out->f_mode & FMODE_WRITE)
- error = do_tee(in, out, len, flags);
- fput_light(out, fput_out);
- }
- }
- fput_light(in, fput_in);
- }
+ if (!in)
+ goto out;
+
+ if (!(in->f_mode & FMODE_READ))
+ goto unlock_in;

+ error = -EIO;
+ if (!file_hotplug_read_trylock(in))
+ goto fput_in;
+
+ error = -EBADF;
+ out = fget_light(fdout, &fput_out);
+ if (!out)
+ goto unlock_in;
+
+ if (!(out->f_mode & FMODE_WRITE))
+ goto fput_out;
+
+ if (!file_hotplug_read_trylock(out))
+ goto fput_out;
+
+ error = do_tee(in, out, len, flags);
+
+ file_hotplug_read_unlock(out);
+fput_out:
+ fput_light(out, fput_out);
+unlock_in:
+ file_hotplug_read_unlock(in);
+fput_in:
+ fput_light(in, fput_in);
+out:
return error;
}
--
1.6.3.1.54.g99dd.dirty


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