Currently, the maximum file size that is supported is 2G. This may be
too small in some cases. For example, kexec_file_load() system call
loads initramfs. In some netboot cases initramfs can be rather large.

Allow to use up-to ssize_t bytes. The callers still can limit the
maximum file size via buf_size.

Signed-off-by: Pasha Tatashin <pasha.tatas...@soleen.com>
---
 fs/kernel_read_file.c            | 38 ++++++++++++++++----------------
 include/linux/kernel_read_file.h | 32 +++++++++++++--------------
 include/linux/limits.h           |  1 +
 3 files changed, 36 insertions(+), 35 deletions(-)

diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c
index 1b07550485b9..5d826274570c 100644
--- a/fs/kernel_read_file.c
+++ b/fs/kernel_read_file.c
@@ -29,15 +29,15 @@
  * change between calls to kernel_read_file().
  *
  * Returns number of bytes read (no single read will be bigger
- * than INT_MAX), or negative on error.
+ * than SSIZE_MAX), or negative on error.
  *
  */
-int kernel_read_file(struct file *file, loff_t offset, void **buf,
-                    size_t buf_size, size_t *file_size,
-                    enum kernel_read_file_id id)
+ssize_t kernel_read_file(struct file *file, loff_t offset, void **buf,
+                        size_t buf_size, size_t *file_size,
+                        enum kernel_read_file_id id)
 {
        loff_t i_size, pos;
-       size_t copied;
+       ssize_t copied;
        void *allocated = NULL;
        bool whole_file;
        int ret;
@@ -58,7 +58,7 @@ int kernel_read_file(struct file *file, loff_t offset, void 
**buf,
                goto out;
        }
        /* The file is too big for sane activities. */
-       if (i_size > INT_MAX) {
+       if (i_size > SSIZE_MAX) {
                ret = -EFBIG;
                goto out;
        }
@@ -124,12 +124,12 @@ int kernel_read_file(struct file *file, loff_t offset, 
void **buf,
 }
 EXPORT_SYMBOL_GPL(kernel_read_file);
 
-int kernel_read_file_from_path(const char *path, loff_t offset, void **buf,
-                              size_t buf_size, size_t *file_size,
-                              enum kernel_read_file_id id)
+ssize_t kernel_read_file_from_path(const char *path, loff_t offset, void **buf,
+                                  size_t buf_size, size_t *file_size,
+                                  enum kernel_read_file_id id)
 {
        struct file *file;
-       int ret;
+       ssize_t ret;
 
        if (!path || !*path)
                return -EINVAL;
@@ -144,14 +144,14 @@ int kernel_read_file_from_path(const char *path, loff_t 
offset, void **buf,
 }
 EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
 
-int kernel_read_file_from_path_initns(const char *path, loff_t offset,
-                                     void **buf, size_t buf_size,
-                                     size_t *file_size,
-                                     enum kernel_read_file_id id)
+ssize_t kernel_read_file_from_path_initns(const char *path, loff_t offset,
+                                         void **buf, size_t buf_size,
+                                         size_t *file_size,
+                                         enum kernel_read_file_id id)
 {
        struct file *file;
        struct path root;
-       int ret;
+       ssize_t ret;
 
        if (!path || !*path)
                return -EINVAL;
@@ -171,12 +171,12 @@ int kernel_read_file_from_path_initns(const char *path, 
loff_t offset,
 }
 EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns);
 
-int kernel_read_file_from_fd(int fd, loff_t offset, void **buf,
-                            size_t buf_size, size_t *file_size,
-                            enum kernel_read_file_id id)
+ssize_t kernel_read_file_from_fd(int fd, loff_t offset, void **buf,
+                                size_t buf_size, size_t *file_size,
+                                enum kernel_read_file_id id)
 {
        struct fd f = fdget(fd);
-       int ret = -EBADF;
+       ssize_t ret = -EBADF;
 
        if (!f.file || !(f.file->f_mode & FMODE_READ))
                goto out;
diff --git a/include/linux/kernel_read_file.h b/include/linux/kernel_read_file.h
index 575ffa1031d3..90451e2e12bd 100644
--- a/include/linux/kernel_read_file.h
+++ b/include/linux/kernel_read_file.h
@@ -35,21 +35,21 @@ static inline const char *kernel_read_file_id_str(enum 
kernel_read_file_id id)
        return kernel_read_file_str[id];
 }
 
-int kernel_read_file(struct file *file, loff_t offset,
-                    void **buf, size_t buf_size,
-                    size_t *file_size,
-                    enum kernel_read_file_id id);
-int kernel_read_file_from_path(const char *path, loff_t offset,
-                              void **buf, size_t buf_size,
-                              size_t *file_size,
-                              enum kernel_read_file_id id);
-int kernel_read_file_from_path_initns(const char *path, loff_t offset,
-                                     void **buf, size_t buf_size,
-                                     size_t *file_size,
-                                     enum kernel_read_file_id id);
-int kernel_read_file_from_fd(int fd, loff_t offset,
-                            void **buf, size_t buf_size,
-                            size_t *file_size,
-                            enum kernel_read_file_id id);
+ssize_t kernel_read_file(struct file *file, loff_t offset,
+                        void **buf, size_t buf_size,
+                        size_t *file_size,
+                        enum kernel_read_file_id id);
+ssize_t kernel_read_file_from_path(const char *path, loff_t offset,
+                                  void **buf, size_t buf_size,
+                                  size_t *file_size,
+                                  enum kernel_read_file_id id);
+ssize_t kernel_read_file_from_path_initns(const char *path, loff_t offset,
+                                         void **buf, size_t buf_size,
+                                         size_t *file_size,
+                                         enum kernel_read_file_id id);
+ssize_t kernel_read_file_from_fd(int fd, loff_t offset,
+                                void **buf, size_t buf_size,
+                                size_t *file_size,
+                                enum kernel_read_file_id id);
 
 #endif /* _LINUX_KERNEL_READ_FILE_H */
diff --git a/include/linux/limits.h b/include/linux/limits.h
index b568b9c30bbf..f6bcc9369010 100644
--- a/include/linux/limits.h
+++ b/include/linux/limits.h
@@ -7,6 +7,7 @@
 #include <vdso/limits.h>
 
 #define SIZE_MAX       (~(size_t)0)
+#define SSIZE_MAX      ((ssize_t)(SIZE_MAX >> 1))
 #define PHYS_ADDR_MAX  (~(phys_addr_t)0)
 
 #define U8_MAX         ((u8)~0U)
-- 
2.36.1.124.g0e6072fb45-goog


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